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MAGNESITE 


IN 


CALIFORNIA 


BULLETIN  No.  79 


]$S>m.O  iJY  THE 


CALIFORNIA  STATE  MINING  BUREAl 

FERRY  BUILDING,  SAN  FRANQSCO 


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THE  LIBRARY  OF  THE 
UNIVERSITY  OF  CALIFORNIA 

DAVIS 


F.  S.  D-" 

P*»0  K  I  V  e  D 

I  NOV  2  5  1925 
LIBRARY 


CALIFORNIA  STATE  MINING  BUREAU 

FERRY  BUILDING,  SAN  FRANCISCO 
LLOYD  L.  ROOT 


State  Mineralogist 


San  Francisco] 


BULLETIN  No.  79 


[May,  1925 


MAGNESITE 


IN 


CALIFORNIA 


By 
WALTER  W.  BRADLEY 


CALIFORNIA    STATE    I'RINriNG    OFFICE 

JOHN  E.  KING,  State  Printer 

SACRAMKNTO,   1925 

LIBRARY 

UNIVERSITY  OF  CALIFORNIA 
DAVIS 


CONTENTS. 

Page 

LETTER  OF  TRANSMITTAL 7 

TREFACE  8 

INTRODUCTION 9 

Properties    and   Origin 10 

Industrial  Applications  and  Uses 13 

Testing  and  Specifications  for  Magnesium  Oxychloride  Cements 21 

Production  and  Prices 33 

Tariff  avd  Importations 38 

Bibliography 39 

CALIFORNIAN    MINES    AND    PLANTS 41 

Alameda  County 41 

Fresno  County 44 

Kern   County 47 

Kings  County 51 

Los  Angeles  County 52 

Mendocino  County 52 

Merced  County 52 

Monterey  County 53 

Napa  County 53 

Nevada    County 58 

Placer   County 59 

Riverside    County 61 

San  Benito  County 66 

San  Bernardino  County 72 

San  Diego  County _- 76 

San  Luis  Obispo  County 7fi 

Santa   Barbara   County 77 

Santa  Clara  County 78 

Sonoma  County 89 

Stanislaus   County 98 

Tulare  County 103 

Tuolumne    County 138 


94580 


ILLUSTRATIONS. 


PHOTOGRAPHS. 

Page 

1.  Magnesite  specimen  showing  conchoidal  fracture.     From  No.  4  Tunnel,  Tulare 

mine  of  Sierra  Magnesite  Company,  near  Success,  Tulare  County 10 

2.  Magnesite  specimen  showing  conchoidal  fracture.     From  Stanislaus  County__     10 

3.  Magnesite    from    Rolling    deposit   near    Preston,    Sonoma    County,    California, 

showing  shrinlcage  cracks 12 

4.  Magnesite  from  Kolling  deposit,   Sonoma  County,  showing  pitted  surface  due 

to  weathering 14 

5.  Magnesite  from  Sonoma  Magnesite  Company's  mine  Sonoma  County,  showing 

parallel   shrinlcage   cracks 14 

C.  Cedar  Mountain  magnesite  mine,  Alameda  County 40 

7.   Open  cut   (glory  hole)   in  Cedar  Mountain  magnesite  mine 40 

S.  Flat-hearth  calcining  furnace,  at  Cedar  Mountain  magnesite  mine 42 

9.   Pellets  of  hydro-magnesite  in  serpentine  in  Sec.  34,  T.  4  S.,  R.  3  B.,  M.  D.  M., 

Alameda   County 43 

10.  Magnesite  calcining  furnace  of  Sinclair  Bros.    (Ferguson),  at  Piedra,  Fresno 

County    45 

11.  General  view  of  Bissell  magnesite  mine,  looking  eastward 47 

12.  Bissell  magnesite  deposit,  showing  stratification,  also  folding  and  faulting 48 

13.  Bissell  magnesite  deposit,  showing  stratification,  also  dip  to  south 49 

14.  Scott    fine-ore    quicksilver    furnace    at   Kings    mine.    Kings    County,    used    for 

calcining   magnesite    51 

15.  Calcining  plant  at  Maltby  No.  2  mine.  Chiles  Valley,  Napa  County.     Producing 

dead-burned  magnesite  in  a  rotary  kiln 54 

IC.  White  Rock  mine  in  Pope  Valley,  Napa  County 57 

17.  Calcining  plant  at  White  Rock  mine.  Pope  Valley,  Napa  County 58 

18.  Stockwork  of  magnesite  veins  in  open-cut  at  Hemet  magnesite  mine.  Riverside 

County    61 

19.  General  view  of  Hemet  magnesite  mine,   looking  westward  from  top  of  hill 

across  Hemet  Valley,  Riverside  County 63 

20.  Hemet  magnesite  mine,  looking  eastward,  showing  dumps  and  plant 63 

21.  Outcrop  of  magnesite  at  Sampson  magnesite  mine,  San  Benito  County 64 

22.  South  open-cut  at  Sampson  magnesite  mine,  Oct.  2,   1917,  before  installation 

of   aerial    tram 66 

23.  Quarries  and  ore-bins  of  Sampson  magnesite  mine,  taken  from   aerial   tram, 

November  8,   1923  —  -- 67 

24.  Main  open-cut  at  Sampson   (Maltby  No.   3)   magnesite  mine,  near  New  Idria, 

San  Benito  County,  November,   1923 07 

25.  Calcining  magnesite  in  vertical  kilns,  at  Sampson  mine,  October,  1917 68 

26.  Interior   of   vertical,   magnesite-calcining   furnace   of   Hoff-Price   Company   at 

Sampson  mine,  under  construction  Oct.  2,   1917 69 

27.  Calcining  plant  at  Maltby  No.  3    (Sampson)   magnesite  mine,  producing  dead- 

burned  refractory  magnesite,   November,   1923 69 


ILLUSTRATIONS.  5 

Page 

28.  Rotary  kiln  at  Maltby  No.  3  (Sampson)  magnesite  mine,  San  Benito  County—     70 

29.  Magnesite  outcrop  on  the  ClifEside  claim,  near  Afton,  San  Bernardino  County_     73 

30.  Afton  magnesite  deposit,  showing  outcrop  on  the  Hill  Top  claim 73 

31.  Magnesite  exposure  on  the  Quaker  Group,  southeast  of  Cima,  San  Bernardino 

County    '^4 

32.  Plant    of    International    Magnesite    Company    (now    Duralite    Company),    at 

Chula  "Vista,   San  Diego  County 76 

33.  Open-cut  of  "^''estern  Magnesite  Development  Company   (in  1915) 83 

34.  Plant    and    mines    of    \A'estern    Magnesite    Development    Company     (Maltby 

No.    1),   looking  easterly 84 

35.  South  end   (White  Queen)  workings  at  Maltby  No.  1  mine 86 

36.  Tramming  ore  from  north  end  of  White  Diamond  workings,  at  Maltby  No.   1 

mine    (Western  Magnesite  Development  Company)   on  Red  Mountain 87 

37.  Vertical  kiln  of  Western  Magnesite  Development  Company 88 

38.  Scott,    fine-ore,    quicksilver   furnace    in    use   for   calcining   magnesite    fines   at 

Maltby  No.   1  mine 88 

39.  Kiln  of  the  Refractory  Magnesite  Company,  east  of  Preston,  Sonoma  County_     90 

40.  Vein   of  magnesite   as   exposed    in    an    open-cut    on   the   Alfred   Claim   of  the 

Sonoma  Magnesite  Company,  Sonoma  County 93 

4).   Ore  chute  at  upper  deposit  of  Sonoma  Magnesite  Company 94 

4-.  Rotary  kiln  of  Sonoma  Magnesite  Company,  at  Magnesite,  Sonoma  County 95 

43.  Magnesite  calcining  furnace  of  the  Western  Carbonic  Acid  Oas  Company,  at 

Guerneville,    Sonoma   County 96 

44.  Mines  of   Oustine   Magnesite   Company    (left)    and   Howard   Cattle    Company 

(right),  in  Stanislaus  County  west  of  Ingomar 100 

4.">.   Magnesite  loading-bunkers  at  Ingomar.  for  the  Gustine  magnesite  and  Howard 

Cattlf  Company  mines 101 

4t).   Magnesite  vein  3  feet  thick,  in  No.  3  workings  of  Lindsay  mine,  near  Success, 

Tulare   County    103 

4  7.   Slickenside  magnesite,  showing  effect  of  movement  along  the  vein,   in   tunnel 

of  Lindsay   Mining  Company 105 

48.  View  northward  showing  blanket  veins  being  worked  on  the  property  of  the 

Porterville  Magnesite  Company  in  1917 110 

49.  Southerly  side  of  'north'  hill    (Harker  mine)    from  the  south,   showing  both 

'gash'  and  'blanket'  veins 112 

50.  North  end  of  'north'  hill  of  Harker  mine.     Portion  of  'Oakland'  mine  of  Sierra 

Magnesite  Company  in  foreground 114 

51.  Calcining    plant    at    Harker    mine     (Porterville    Magnesite    Company),    near 

Porterville,  Tulare  County 116 

52.  Sierra  Magnesite  Company's   properties   on   South   Fork   of  Tule   River,    near 

Success,  Tulare  County 120 

53.  Vertical   kilns  of  the  Tulare   Mining  Company    (now  Sierra  Magnesite),   at 

Magnesite  Station,  Tulare  County 121 

54.  Ore  dumps,  at  'A-South'  opening.  Sierra  Magnesite  Company 122 

55.  Stockwork  of  veins  at  'Lower'  quarry  on  Sierra  'Standard'  workings 126 


6  ILIiUSTRATIONS. 

Page 
5fi.   Stoikwork    of   veins    in    No.    fl    Quarry    ('South    Summit    Quarry")    at    Sierra 

'Standard'   workings    127 

57.  Sloping  vein  in  No.  22  Tunnel,  'Oakland'  ground  of  Sierra  Magnesite  Company  128 

58.  Calcining  plant  of  Sierra  Magnesite  Company  at  Porterville,  Tulare  County 130 

59.  Rotary  kilns  of  the  Sierra  Magnesite  Company  at  Porterville 131 

60.  Cooling  floor,  Sierra  Magnesite  Company,  Porterville 134 

61.  Two  banks  containing  12  buhr  mills,  Sierra  Magnesite  Company,  Porterville 136 

62.  Vail   and  Maxwell   calcining  plant   at   Chinese  Camp,   Tuolumne   County,    for 

handling  magnesite  from  the  Gray  Eagle  mine 138 

PLATES. 

I.   Outline  map  of  California  showing  location  of  magnesite  deposits 10 

II.   Cross-bending  testing  machine 32 

III.   Berry  strain  gauge 33 

/^  IV.   Chart   showing  production   and   average   value   of  magnesite   in   California, 

1887-1924    (inc.)    36 

V.   Sketch  showing  approximate  section  through  Bissell  magnesite  deposit 48 

VI.   Sketch  map  and  vertical  section  of  Afton  Magnesite  Group,  San  Bernardino 

County     72 

VII.   Sketch  map  of  magnesite  deposits  on  Red  Mountain,  Santa  Clara  County 82 

VIII.   Map  showing  claims  and  workings  of  the  Western  Magnesite  Development 

Company  (Maltby  No.  1  mine),  on  Red  Mountain,  Santa  Clara  County_  82 

IX.   Map  of  White  Diamond  (north  end)  workings  of  Maltby  No.  1  mine 84 

X.  Map  showing  locations  of  magnesite  deposits  in  the  vicinity  of  Porterville, 

Tulare  County,   California 104 

XI.  Flow-sheet    of    magnesite    plant    of    the    Sierra    Magnesite    Company    at 

Porterville 132 


LETTER  OF  TRANSMITTAL. 

June  15,  1925. 

To  His  Excellency,  The  Honorable  Friend  Wm.  Richardson, 
Governor  of  the  State  of  California. 

Sir:  1  have  the  honor  to  lierevvith  transmit  Bulletin  No.  79  of  the 
State  ]\Iining  Bureau,  on  Magnesite  in  California. 

This  work  deals  in  detail  with  one  of  California's  very  important 
non-metallic  mineral  resources.  California  was  for  many  years  the 
sole  domestic  producer  of  magnesite  in  the  United  States,  and  still 
leads.  The  commercial  uses  for  magnesite  are  expanding  and  daily 
increasing  in  importance;  so  that  there  is  now  an  active  demand  for 
such  data  and  information  as  this  bulletin  makes  available  to  the  public. 

Respectfully  submitted. 

Lloyd  L.  Root, 
State  Mineralogist. 


PREFACE. 


Originally  the  manuscript  for  this  bulletin  on  California's  magne- 
site  resources  was  prepared  following  a  special  field  survey  made  by  the 
staff  of  the  State  Mining  Bureau  during  the  spring  and  summer  of 
1917.  There  was  an  acute  demand  for  domestic  magnesite  at  that 
time  due  to  the  situation  brought  about  by  the  war  in  Europe.  Besides 
the  present  author,  the  Bureau's  engineers  participating  in  that  sur- 
vey Avere :  Messrs.  Clarence  A.  Waring,  Emile  Huguenin,  W.  Burling 
Tucker,  and  Clyde  McK.  Laizure.  Lack  of  available  funds  for  print- 
ing prevented  publication  at  that  time.  Late  in  1918  the  manuscript 
was  revised,  mainly  by  Mr.  Waring  (since  deceased),  and  again  pre- 
pared for  publication,  but  again  it  was  held  up  for  lack  of  printing 
funds. 

With  the  resumption  of  foreign  importations  shortly  after  the  close 
of  hostilities  in  Europe,  there  was  a  sharp  break  in  the  domestic 
production  of  magnesite.  Following  the  placing  of  a  moderate  customs 
duty,  coupled  with  the  expanding  growth  of  the  plastic  trade,  the 
situation  has  improved  materially  for  the  domestic  producers  of 
magnesite,  particularly  in  California.  There  is  a  healthy  demand  for 
the  Californian  mineral  because  of  its  adaptability  for  plastic  purposes. 

For  this  reason,  the  present  author  has  recently  made  a  resurvey 
of  the  more  important  districts  in  the  state,  bringing  up  to  date  the 
various  changes  in  ownership  and  plant  installations,  and  adding  notes 
relative  to  certain  new  discoveries.  The  data  relative  to  Placer  County 
were  verified  in  1924  by  Mr.  C.  A.  Logan,  district  engineer  of  the 
Bureau  at  Sacramento ;  and  the  data  on  Kiverside  and  San  Bernardino 
counties  verified  by  Mr.  W.  Burling  Tucker,  district  engineer  at  Los 
Angeles.  New  data  on  standardization,  specifications,  and  testing  prac- 
tices are  also  included. 

Walter  W.  Bradley. 
San  Francisco,  May  15,  1925. 


INTRODUCTION. 


Magnesite  is  known  to  tlie  iivnin-al  public  solely  as  a  structural  and 
industrial  material.  It  has  been  exploited  and  utilized  for  such  pur- 
poses for  many  years,  during  which  time  it  has  earned  an  enviable 
reputation  and  reached  an  important  position  among  mineral  products. 

Strictly  speaking,  magnesite  is  also  an  ore  of  the  metal  magnesium, 
but  as  such  it  has  never  shared  in  the  common  knowledge  which  the 
public  has  of  ores  of  the  better  known  metals,  nor  enjoyed  the  universal 
interest  which  metallic  minerals  usually  excite.  For  this  reason, 
although  magnesite  is  neither  unusual  nor  rare,  it  can  hardly  l)e  said 
to  be  a  conunon  mineral.  It  is  interesting  to  note  that,  in  the  United 
States,  deposits  of  connuercial  size  are  as  yet  unknown  outside  of  Cali- 
fornia and  Washington. 

Extensive  deposits  of  exceptionally  high-grade  magnesite  have  been 
knoAvn  for  many  years  to  exist  in  California.  An  early  list  of  the 
known  deposits  i)ublished  in  the  Sixth  Annual  Report  of  the  State 
^lineralogist.^  included  occurrences  in  no  less  than  nine  counties. 

Altliough  there  was  no  commercial  production  from  these  deposits  at 
the  time,  their  potential  value  to  the  state  was  clearly  recognized. 
Actual  production  began  a  little  later,  in  1886,-  with  the  shipment 
of  a  small  tonnage  from  Cedar  Mountain  in  Alameda  County;  but 
the  exact  figures  are  not  recorded.  In  commenting  on  the  presence 
of  magnesite.  among  other  things,  the  Hanks  report  said:  "The  Cali- 
fornia mineral  will  be  turned  to  account  at  some  future  time,  when 
it  will  be  interesting  and  important  to  know  where  it  may  be  found.'' 
The  magnesite  industry  today  witnesses  the  fulfillment  of  that 
prophecy. 

Conditions  governing  the  production  and  consumption  of  domestic 
magnesite  have  been  such,  however,  that  there  Avas  comparatively 
little  actual  realization  from  these  valuable  natural  assets  until 
changes  brought  on  by  the  European  war  made  it  possible  to  fully 
develop  and  exploit  the  state's  resources  in  this  important  mineral. 

Before  the  war  nearly  all  the  magnesite  used  for  refractory  pur- 
poses in  the  I'^nited  States  was  imported.  It  was  used  as  linings  for 
basic  steel  furnaces  and  converters,  and  in  other  melting  and  heating 
furnaces  in  metallurgical  works.  The  principal  market  for  refractories 
was  (and  still  is)  in  the  eastern  steel  centers;  and  cheap  foreign  labor 
and  low  ocean  freight  rates  gave  foreign  magnesite  a  commercial 
advantage  over  that  produced  in  the  west. 

According  to  Gale  ^  "In  1912  the  quantity  of  crude  and  calcined 
magnesite  imported  *  *  *  ^r.^  *  *  *  20  times  the  domestic 
production. ' '  Domestic,  in  this  instance,  means  California ;  for  up 
to  the  end  of  1916  California  was  the  only  state  of  record  in  the  United 
States,  producing  magnesite  in  commercial  quantities.  In  fact,  there 
was  no  production  outside  the  state  on  the  North  American  Continent. 
The  Washington  deposits  became  a  factor  in  supplying  the  refractories 
market,  in  1917. 

'Hanks.  H.  C,.,  Sixth  annual  report  of  the  State  Mineralogist:  Cal.  State  Min. 
Bur.,   Report  VI.  Part  I,  p.   119,   1886. 

=  U.  ,S.  Geol.  Surv.,  Mineral  Resources  of  the  U.  S.,  1886,  pp.  6,  696,  1887. 

'  Gale,  H.  S.,  Magnesite  dti)0sits  in  California  and  Nevada :  U.  S.  Geol.  Surv. 
Bull.    540,   page    484,    1914. 


10 


CALIFORNIA    STATE    TVIININO    BUREAU. 


Photo  No.  1 — Magnesite  specimen  showing-  conchoidal  fracture.  From  No.  4 
Tunnel,  Tulare  Mine  of  Sierra  Magnesite  Company,  near  Success, 
Tulare   County.      TAvo-thirds  natural   size. 


Photo    No.    2 — Magnesite    Specimen    showing    conchoidal    fracture. 
From  Stanislaus  County.     Two-thirds  natural  size. 


CALl  FORNIA  STATE  M!\'ING  BUREAU- 

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STATE  MIHEWCCCIST 


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MAGNESITE    IN    CALIFORNIA.  11 

Although  the  output  of  ('alifornia  liad  o-rowii  from  a  beginning  in 
1887  of  600  tons,  to  an  average  of  a])0ut  10,000  tons  of  crude  per  year 
between  1908  and  1914  inclusive,  the  entire  production  was  practically 
all  consumed  on  the  Pacific  Coast,  the  greater  portion  being  utilized 
in  the  'sulphite  proce\ss'  of  manufacturing  wood-pulp  paper. 

The  disruption  of  shipping  and  cutting  off  of  foreign  supplies,  due 
to  the  war,  soon  made  it  necessary  for  eastern  consumers  to  depend 
largely  on  domestic  sources  for  magnesite,  and  to  offer  much  higher 
prices  than  formerly  prevailed.  The  stimulating  effect  of  heavy 
demand  and  high  prices  began  to  be  felt  by  the  magnesite  industry 
of  the  state  late  in  1914.  The  production  in  1915  was  more  than 
double  that  of  the  previous  year,  and  a  large  percentage  of  the  mineral 
was  shipped  east  to  be  used  for  refractory  purposes.  Increasing  prices, 
as  foreign  material  became  still  more  scarce  in  the  market,  led  to  sub- 
stantial capital  investment  in  magnesite  properties.  Many  new  deposits 
were  developed,  old  ones  were  reopened  and  new  and  larger  calcining 
plants  were  constructed,  at  various  points  in  the  state.  The  expan- 
sion of  the  industry  was  remarkable.  The  1916  production  of  magne- 
site showed  a  5-fold  increase  over  that  of  1915,  and  reached  a  value 
of  11  million  dollars.  Mining  activities  in  1917  were  marked  by  a 
slower  but  healthy  growth.  The  increase  in  tonnage  approximated 
33';^ ,  and  the  total  value  of  the  crude  closely  approached  2  million 
dollars.  At  the  present  time,  though  the  principal  consumption  of 
Cahfornian  magnesite  is  west  of  the  Mississippi  River,  there  is  some 
tonnage    going  to  the  Atlantic  seaboard,  via  the  Panama  Canal. 

Magnesite  has  widely  divergent  applications  in  the  industrial  arts. 
These  are  not  entirely  distinct  but  they  may  be  roughly  divided  into 
i-efractory  uses,  plastic  uses,  and  chemical  or  miscellaneous.  It  was 
the  absolute  necessity  for  suitable  refractory  materials,  in  connection 
with  the  manufacture  of  steel  and  in  other  metallurgical  processes, 
that  made  the  domestic  production  of  this  mineral  of  such  prime 
importance  to  the  nation  during  the  \var  period.     Chas.  G.  Yale  ^  says : 

"Were    an    the    known    deposits    in    California    brought    to    their    capacity    of    pro- 
auction,    It    would    l)e   difficult    for    them    to    furnish    the    magnesite    needed'  annually 
the     United     Mates     for     refractory     purposes.       They    could     easily     meet,     how- 
ever,   both    in   quantitiy   and   quality,    the   domestic   demand   for   the   purer   grades   of 
othfr^produ"^tl  "  l^^^l^^r,    cement,    paints,    fireproof   and    damp-proof   coalings,    and 

The  latter  uses  were,  of  course,  subordinate  while  the  war  lasted 
to  those  affecting  the  output  of  steel  and  the  efficiency  of  other  war 
industries;  but  many  magnesite  products  which  were  developed,  and 
are  being  developed,  by  peaceful  competition,  have  been  found  extremely 
well  adapted  to  the  ])urposes  for  which  intended,  so  that  on  the  whole 
It  may  be  safely  said,  that  in  its  large  and  varied  field  of  usefulness 
magnesite  has  no  substitute. 

PROPERTIES  AND  ORIGIN. 

Magnesite  is  a  mineral  of  simple  composition,  it  being  e.ssentiallv 
a  magnesium  carbonate  (MgCO,),  eciuivalent  to  magnesium  oxide, 
called  'magnesia,'  (MgO)  -f  carbon  dioxide  (COJ. 

Limestone,  the  massive  form  of  the  mineral  calcite,  is  a  calcium 
carbonate  (CaCO,)  composed  of  calcium  oxide,  called  'lime'  (CaO)  + 
carbon  dioxide  (CO2). 

'  U.  S.  Geol.  Surv. :  Min.  Res.  of  the  U.  S.  1915,  Part  II,  page  1020. 


12 


CALIFORNIA    STATE    MINING   BUREAU. 


From  the  above  it  will  be  seen  that  the  two  minerals  calcite  and 
magnesite  are  closely  related  chemically.  Limestone  (calcite)  when 
heated,  gives  off  the  gas  CO,,  and  lime  or  calcium  oxide  remains,  the 
metallic  base  of  which  is  the  element  calcium.  Similarly  magnesite 
when  heated  gives  off  CO2  and  magnesia  or  magnesium  oxide  remains. 
Its  base  is  the  metal  magnesium.  Pure  magnesite  contains  47.6% 
magnesia  (MgO)  and  52.4%  carbon  dioxide  (COJ. 

Calcium  and  magnesium  are  inter-replacable,  one  with  the  other,  in 
all  proportions,  in  these  carbonates ;  and  when  the  chemical  combination 
is  in  equal  proportions,  we  have  the  mineral,  dolomite,   (CaMg)C03. 

Magnesite  usually  occurs  as  a  white,  compact,  fine-grained,  ma.ssive 
mineral.  Its  color  may  vary,  according  to  the  degree  of  purity,  to 
yellowish  or  grayish,  white  and  brown.     Crystalline  structure  is  rare, 


Photo  No.  3 — Magnesite  from  Kolling  deposit  near  Preston, 
Sonoma  County,  sliowing  slirinliage  cracks.  Two-thirds 
natural   size. 

except  in  Austria  and  Washington.  Impure  varieties  are  sometimes 
coarsely  granular  or  earthy.  When  earthy  it  is  often  mixed  with 
hydrated  silicate  of  magnesia  (sepiolite,  or  meerschaum)  ;  in  fact,  early 
mineralogists  at  first  considered  meerschaum  to  be  a  siliceous  variety  of 
magnesite. 

The  common  massive  form  has  a  dull  luster,  hardness  of  from  3.5  to 
4.5  and  shows  a  smooth  conchoidal  fracture  resembling  unglazed 
porcelain.  (See  Photos  1  and  2.)  If  cold  dilute  hydrochloric  acid 
(HCl)  be  dropped  upon  it  no  action  takes  place,  but  hot  acid  will  cause 
effervescence.  Various  proportions  of  silica,  alumina,  lime  and  iron 
oxides  are  often  present  as  impurities. 

Bodies  of  magnesite  of  workable  size  according  to  Eckel  ^ 

"occur  commonly  in  one  of  three  associations  the  methods  of  origin  of  the  deposits 
being  different  in  each  case.     The  three  types  of  deposits  are  : 

» Eckel,  E.  C,  Cements,  Limes  and  Plasters,  p.  149,  1905. 


MAGNESITE   IN    CALIFORNIA.  13 

1.  Magnesite  occurs  most  commonly  in  the  form  of  irregular  veins  or  pockets  in 
serpentine  or  other  magnesian  igneous  rocks.'  In  this  case  the  magnesite  has  been 
formed  as  a  decomposition  product  arising  from  the  decay  of  the  igneous  rocks. 

2.  Magnesite  occurs  in  the  form  of  beds  associated  with  deposits  of  rock  salt, 
gypsum,  etc.  In  this  case  the  magnesite  deposit  has  undoubtedly  originated  by 
direct  deposition  of  magnesium  carbonate  from  bodies  of  concentrated  saline  waters. 

3.  Magnesite  also  occurs  in  the  form  of  beds  interstratified  with  shales,  limestones, 
etc.  Magnesite  deposits  of  this  type  are  commonly  ascribed  to  the  replacement  of 
the  lime  (in  a  limestone)  by  magnesia  carried  in  by  percolating  waters.  This 
may  be  true  in  some  cases,  but  such  deposits  may  also  have  originated  by  direct 
deposition,   as  described  under    (2)    above." 

Gale/  referring  to  thef  magnesite  deposits  of  California  and  Nevada, 
says : 

"Most  of  the  deposits  of  magnesite  known  are  associated  with  intrusive  igneous 
rocks  such  as  peridotite  and  allied  basic  rocks,  which  are  composed  essentially 
of  minerals  rich  in  magnesia,  like  olivine  and  the  pyroxenes.  As  the  magnesite 
occurs  in  veins  and  lodes,  in  part  replacing  the  igneous  rock,  it  seems  quite  clear 
that  it  is  derived  mainly  from  the  alteration  of  the  intrusive  magnesian  rock.  In 
the  original  rock  the  magnesia  is  present  principally  in  the  form  of  silicates. 
By  alteration  of  the  silicates  to  the  carbonate,  magnesite,  the  silica  is  set  free.  The 
magnesite  veins  commonly  occur  in  zones  of  more  intensive  alteration  in  the 
magnesian  silicate  country  rocks,  and  these  zones  are  most  conspicuously  charac- 
terized by  secondary  silica,  as  opal,  chalcedony,  or  quartz.  One  of  the  most 
common  products  of  the  decomposition  by  hydration  or  weathering  of  magnesia-rich 
silicate  rocks  is  the  green  mineral  serpentine,  a  magnesian  silicate,  with  water  in 
combination,  and  this  alteration  takes  place  so  extensively  over  the  surface  areas 
of  the  basic  intrusive  rocks  here  described  that  the  whole  mass  is  commonly 
referred  to  as  'serpentine',  although  that  term  strictly  signifies  a  specific  mineral 
rather  than  a  rock  that  is  more  or  less  diverse  in  composition." 


INDUSTRIAL  USES. 

Magnesite  is  identified  with  a  large  and  growing  variety  of  industrial 
nses.     Its  leading  applications  are  summarized  as  follows : 

1.  For  refraetoiy  purposes,  as  fire  brick  or  in  monolithic  form  for 
metallurgical  furnace  and  converter  linings,  furnace  hearths,  cru- 
cibles, etc. 

2.  Plastic  purposes.  Calcined  and  ground  for  oxychloride  or  Sorel 
cement. 

3.  In  the  manufacture  of  wood-pulp  paper. 

4.  For  making  carbonic  acid  gas. 

5.  Both  crude  and  calcined,  for  heat  insulation  and  miscellaneous 
applications. 

6.  For  making  refined  magnesia  salts. 

7.  As  a  source  of  the  metal  magnesium. 

Refractory    Products. 

The  use  of  magnesite  for  refractory  purposes  is  undoubtedly  its  most 
important  application,  at  least  at  present,  so  far  as  tonnage  require- 
ments are  concerned. 

Infusible,  dense,  chemically-stable  magnesia  is  produced  when  crude 
magnesite  is  subjected  to  complete  calcination.  This  material  is  used 
for  the  lining  of  basic  open-hearth  steel  furnaces,  for  furnace  hearths, 
crucibles,  cupels,  etc.  It  is  also  employed  in  copper  reverberatories 
and  other  special  metallurgical  furnaces  such  as  for  handling  bullion ; 
silver  slimes;  electric  smelting;  heating;  welding  and  melting  furnaces; 
calcium  carbide  kilns;  and  in  the  burning  zone  of  rotary  kilns  in 
Portland  cement  plants.  For  these  purposes  it  is  made  into  magnesia 
brick  or  the  material  is  rammed  into  place  or  plastered  on,  much  as 
concrete  is,  forming  a  one-piece  lining  or  surface. 

'Gale,  H.  S.,  Magnesite  deposits  in  California  and  Nevada:  U.  S.  Geol.  Surv 
Bull.    540,   page    486,    1914. 


14 


CALIFORNIA    STATE    MINING   BUREAU, 


Photo  No.  4 — Magnesite  from  Kolling 
deposit,  Sonoma  County,  showing 
pitted  surface  due  to  weathering. 
Two-thirds  natural  size. 


Photo  No.  5 — Magnesite  from  Sonoma  Magnesite  Com- 
pany's mine,  Sonoma  County,  showing  parallel  shrink- 
age cracks.     Two-thirds  natural  size. 


MAGNESITE   IN    CALIFORNIA.  15 

Crude  magnesite  is  calcined  or  burned,  sometimes  Avith  coke,  in 
vertical-stack  kilns,  or  in  the  more  modern  horizontal  rotary  oil-fired 
kiln.  In  California,  many  stack  kilns  are  also  oil  fired.  The  prop- 
erties of  the  calcined  pi'oduct  vary  with  the  temperature  employed 
and  length  of  time  of  burning.  Light-burned  magnesite  has  a  specific 
gravity  of  3.00  to  8.07 ;  it  will  slake  with  water  and  then  if  exposed 
to  the  air  will  partly  reearbonate  and  harden  slowly,  as  lime  does. 
It  has  considerable  plasticity  and  may  be  moulded  under  pressure  into 
various  shapes.  However,  if  calcination  is  carried  on  at  a  higher 
temperature  or  for  a  longer  period  a  'dead  burned'  magnesia,  having 
a  specific  gravity  of  3.61  to  3.80,  is  produced.  When  dead  burned, 
magnesite  Avill  not  take  up  either  water  or  carbon  dioxide  from  the 
air ;  furthermore  it  possesses  no  plasticity. 

Refractory  magnesia  bricks  and  furnace  linings  are  made  from  a 
mixture  of  the  two  forms  in  the  proportion  of  4  to  6  parts  of  the 
heavy  to  1  of  the  light.  The  dense  inert  magnesia  furnishes  the  base 
while  the  lighter  form  gives  the  mi.xture  plasticity  and  causes  it  to 
harden. 

Although  commonly  believed  that  the  'dead  burned'  product  derived 
from  magnesite  containing  little  or  no  lime,  silica,  oxide  of  iron,  or 
alumina,  is  the  most  refractory,  the  imported  material  formerly  used 
with  satisfactory  results,  contained  from  3%  to  4%  of  silica,  6%  to 
8%  iron  and  up  to  4%  of  lime.  It  is  even  reported^  that  "Some  of 
the  California  magnesite  which  is  very  pure  and  without  iron  is  mixed 
with  10%  of  slag  from  steel  furnaces  before  being  used  for  furnace 
linings." 

The  following  official  analyses  of  magnesite  from  properties  in  vari- 
ous counties  which  appeared  in  a  press  bulletin  -  of  the  U.  S. 
Geological  Survey  clearly  show  the  characteristic,  low-iron  content  of 
the  Californiau  material. 

Analyses  of  crude  and  calcined  magnesite  from  California. 
[Chase  Palmer,  analyst.] 

1  2  3456  78 

SiOo 1.94  2.43  2.26     4.35    12.65    13.88  2.57     14.72 

FeO    1.49  2.40  2.11             1.71               .80             1.49  .89               1.35 

CaO    .67  1.57  1.52             2.11               .95               .27  .80                 .64 

MgO 45.01  43.62  44.10          42.62          40.73          39.60  45.65            39.60 

COo     50.65  50.11  50.18          49.05          44.64          44.62  50.33             43.73 


99.76  100.13  100.17  99.84  99.77  99.86  100.24  100.04 

9                  10                  11  12  13"  14  15  16» 

SiOo 8.73  9.57  1.82  0.50  0.50  2.70  1  67  0.51 

FeO     .97               1.00                 .50  .20  ".43  .23  .31  b.57 

CaO .39  2.83  1.85  1.92  4.90  .80  1.17  2.48 

MgO     ___  43.18  42.48  45.12  45.90  83.17  46.02  45  75  90.30 

CO.     46.31  44.70  50.73  51.68  11.34  50.32  50.95  5.22 


99.58          100.58          100.02          100.20  100.34  100.07  99.85  99.08 

17                    18  19  20  21  22 « 

SiOi    12.05               2.40  0.65  6.37  1.10  5  21 

FeO    2.83               1.44  .33  .35  .72  "1.70 

^i^9, l-S**               -"J-eS  2.65  2.88  1.17  2.18 

MgO     38.88             42.56  45.43  41.55  45.64  89.08 

CO.     44.84            49.94  51.42  49.18  51.20  1.65 

100.58          100.02  100.48  100.33  39.83  99.82 

;^  U.   S.  Geol.  Survey:  Min.  Res.  of  the  U.  S.  1915,  Part  II,  page  1024. 
-  U.  &.  Geol.  Surv:  Press  Bulletin  No.  377,  August,  1918. 
*  Calcined. 
"  Fe^Oj. 


16  CALIFORNIA    STATE    MINING   BUREAU. 

"t.  White  Rock  mine,   bunker,  Pope  Valley,   Napa  County,  Cal. 

2.  White  Rock  mine,  east  vein,  stock  pile,  Pope  Valley,  Napa  County,  Cal. 

3.  White  Rock  mine,   upper  tunnel.  Pope  Valley,  Napa  County,  Cal. 

4.  Tulare  Mining  Co.,  Blanco  mine,  stock  pile.  Chiles  Valley,  Napa  County,  Cal. 

5.  Soda  Creek  mine,    Detert   &   Elder,   south   tunnel,   stock  pile,    Soda  Valley,    Napa 

County,  Cal. 

6.  Soda  Creek  mine,  north  tunnel,  stock  pile. 

7.  Harker  quarry,  stock  pile,  Gilliam  Creek,   Sonoma  County,  Cal. 

8.  Sonoma  Magnesite  Co.,  lower  mine,  stock  pile,  Austin  Creek,  Sonoma  County,  Cal. 

9.  Sonoma  Magnesite  Co.,  upper  mine,  stock  pile. 

10    Cedar  Mountain  mine,  Clark  &  McDonald,  sacked  for  shipping,  Alameda  County, 
Cal. 

11.  Western   Magnesite  Development  Co.,  White  Queen  mine,   250   feet   inside  tunnel, 

Red  Mountain,   Santa  Clara  County,  Cal. 

12.  White  Queen  mine,  stock  pile. 

13.  White  Queen  mine,  kilns. 

14    Pacific  mine,   bunker,  Red  Mountain,   Santa  Clara  County,   Cal. 

is!  Red   Mountain    Magnesite   Co.,   Butcher   mine,   bunker.   Red   Mountain,    Stanislaus 

County,  Cal. 
IG.   Butcher  mine,  cooling  bins. 

17.  McLaughlin    mine,    stock    pile    on    loading    platform,    Bradford   ranch,    Evergreen, 

Santa  Clara  County,   Cal. 

18.  Jackson  mine,  stock  pile,  Cochrane  ranch,  Morgan  Hill,  Santa  Clara  County,  Cal. 

19.  Warwick  mine,  lower  cut,  stock  pile,  Madrone,  Santa  Clara  County. 

20.  Warwick  mine,  upper  cut,  stock  pile. 

21.  Hoff-Price  Co.  mine,   stock  pile,   Sampson   Peak,   San  Benito   County,   Cal. 

22.  Hoff-Price  Co.  mine,  cooling  floor." 

It  further  says : 

"Of  all  the  California  magnesite  here  shown,  that  of  the  White  Rock  Mine  (Nos. 
1,  2,  3),  Napa  County,  Cal.,  is  highest  in  iron  content  and  at  the  same  time 
reasonably  low  in  silica  and  lime.  Material  from  two  small  properties  (Nos.  17-18) 
in  Santa  Clara  County  carries  as  much  iron,  but  one  is  high  in  silica  and  the 
other  is  high  in  lime.  The  White  Rock  Mine  is  supplying  much  of  the  calcined 
magnesite  used  by  steel  mills  on  the  Pacific  coast.  Some  of  the  California  Magnesite 
that  is  very  high  in  silica  is  used  for  plastic  purposes  and  is  said  to  be  satisfactory." 

In  general,  for  smelter  use  the  calcined  magnesite  should  not  contain 
over  8%  CaO,  and  it  must  have  a  minimum  of  85%  MgO  and  less 
than  8%  Si02  or  5%  sesquioxide  (Fe,  Al,  and  Mn),  but  these  percent- 
ages are,  of  course,  subject  to  modification  by  consumers. 

"Most  of  the  refractory  magnesite  that  has  been  in  general  use  has  peculiar  and 
distinctive  properties  that  are  not  found  in  the  magnesite  deposits  of  the  common 
type.  The  value  of  this  refractory  material  depends  not  only  on  its  resistence  to 
the  corrosive  action  of  heat  and  metallic  slags,  but  also  on  the  permanence  of  the 
forms  in  which  it  is  put  into  the  furnace.  This  permanence  is  due  to  a  natural 
bonding  which  tends  to  make  the  loose  crushed  material  cling  together  under 
furnace  heat  and  thus  makes  brick  forms  molded  from  it  more  durable.  Bricks 
and  granular  furnace  bottoms  made  of  magnesite  that  lacks  this  bond  break,  and 
the  magnesite  floats  off  on  the  fluid  molten  metal  and  is  lost  in  the  slag.  Thus, 
though  magnesite  that  contains  a  small  percentage  of  iron  may  be  somewhat  less 
resistant  to  extreme  heat  than  a  purer  form,  the  slight  fusibility  given  to  the 
material  by  the  iron  tends  to  hold  it  in  place.  For  this  reason,  in  part,  a  type  of 
magnesite  so  far  found  only  in  Austria  and  Hungary  has  been  the  principal  source 
of  the  refractory  magnesia  used  in  this  country.  The  purer  magnesite  from  Greece, 
California,  and  elsewhere  is  used  in  making  plaster  or  cement  or  material  for  other 
relatively  minor  uses."  ' 

The  magnesite  developed  in  the  state  of  Washington  is  crystalline, 
resembling  limestone  and  dolomite,  and  carries  a  small  percentage  of 
iron,  being  similar  to  the  Austrian  magnesite  both  in  appearance  and 
composition.  The  colors  vary  through  pink,  gray,  and  almost  black. 
Calcined,  it  is  dark  brown  to  blackish. 

Normally  about  5  to  6  pounds  of  magnesite  are  used  for  every  ton 
of  steel  made  by  the  open-hearth  process;  but  during  the  World  War 
period  the  consumption  was  as  low  as  one-half  pound  while  cheaper, 
though  less-satisfactory  substitutes  were  being  employed  to  make  up 
the  deficiency  in  tonnage  of  magnesite  available. 

»  Gale,  H.  S,  Magnesite:  U.  S.  Genl.  Surv.,  Bull.  666  ('Our  Mineral  Supplies'), 
p.  173,  1919. 


MAGNESITE   IN    CALIFORNIA.  17 

Plastic  Uses. 

The  oxide  and  chloride  of  certain  elements,  when  mixed,  unite  and 
form  a  very  hard  cement.  This  fact  was  discovered  in  1853  by  the 
French  chemist.  Sorel,  who  produced  a  very  hard  cement,  used  by 
dentists,  hy  mixing  zinc  oxide  and  zinc  chloride.  Later  it  was  found 
that  magnesium  oxide  and  magnesium  chloride  also  produced  a  very 
strong  cement.  ' Oxychloride '  or  'Sorel'  cements  is  the  general  name 
given  to  compounds  of  this  type. 

The  use  of  magnesite  in  the  manufacture  of  magnesia  oxychloride 
or  Sorel  cement  is  an  important  one.  Products  into  which  the  cement 
enters  find  many  technical  applications  in  structural  and  other  work, 
and  they  are  apparently  growing  in  popularity. 

The  cement  is  made  by  mixing  fine-grained,  light-calcined  magnesite 
with  a  solution  of  magnesium  chloride  20°-30^  Baume.  The  strength 
of  this  cement  is  exceptional  and  it  is  very  plastic  and  comparatively 
cheap.  It  is  extensively  used  as  a  binder  in  the  manufacture  of  emery 
and  other  grinding  and  polishing  wheels,  where  a  strong  bond  is 
required  to  prevent  bui-sting,  and  in  making  artificial  stone  and  tile. 
The  cement  sets  quickly  and  does  not  freeze  .so  that  it  may  be  used 
at  below-zero  temperatures. 

For  many  structural  purposes  a  filler,  which  commonly  consists  of 
ground  marble,  sand,  sawdust,  cork,  asbestos  or  other  material  com- 
prising from  10%  to  40%  of  the  whole  is  added  together  with  a 
pigment  to  give  any  desired  color,  and  the  composition  is  then  applied 
in  plastic  form.  The  character  of  the  composite  material  will  of 
cour.se,  vary  with  the  filler  used.  A  rough  finished  .stucco  may  be 
made  or  a  smooth  tough  seamless  surface  which  will  take  a  good  wax 
or  oil  polish.  These  compositions  will  hold  firmly  to  a  base  of  wood, 
metal,  or  concrete. 

As  an  example  of  the  formulas  used  in  mixing  such  cements  the 
following  are  quoted  :^ 

"Mixtures  for  the  underlying  or  coarser  layer. 

[Parts  by  weight.] 
1.   15  parts  magnesia. 

10  parts  magnesium  chloride  solution,   20°   Baume. 
10  parts  moist  sawdust. 
(Sets  in  36  hours.) 
-.   10  parts  magnesia. 

10  parts  magnesium  chloride  solution,  28°  Baume. 
5  parts  sawdust. 

(Sets  in  16  hours.) 

3.  20  parts  magnesia. 

15  parts  magnesium  chloiide  solution,  20°  Baume. 

4  parts  ground  cork. 

(Sets  in  24  hours.) 

4.  5   parts  magnesia. 

3   parts  magnesium  chloride  solution,  20°  Baum^. 

5  parts  ashes. 

(Sets  in  24  hours.) 

Mixtures  for  overlying  or  surface  layers. 

,     ,^  [I'arts   by   weight.] 

1.   4  0  jiarts  magnesia. 

;>3  parts  magnesium  chloride  solution,  19°  Baume. 

10  parts  asbestos  powder. 

5  parts  wood   flour. 

1  part  red  oclier. 

(Sets  in  24  hours.) 


Scherer,  Robert— Der  Magnesit,  sem  Vorkommen,  seine  Gewinnung  und  technische 
Verwertung.  pp.  216-217.  A.  Hartleben's  Bibliothek.  Wien  und  Leipzig,   190S. 
2 — 39802 


18  CALIFORNIA    STATE    MINING   BUREAU. 

2.   25  parts  magnesia. 

25  parts  magnesium  chloride,  21°  Baume. 

4  J  parts  wood  flour,  impregnated  with  4  J  parts  Terpentinharzlosung. 

15  parts  yellow  ocher. 

(Sets  in  30  hours.)" 

Most  of  the  desirable  qualities  in  a  flooring  material  such  as  cleanli- 
ness, quietness,  immunity  from  abrasion,  resilience,  appearance,  water- 
proof character,  elasticity,  warmth  or  thermal  insulation,  lightness, 
strength,  etc.,  are  apparently  met  by  various  magnesia-cement  com- 
pounds. They  have  proved  particularly  efficient  as  a  flooring  in  steel 
railroad  coaches  and  in  various  parts  of  ships.  They  are  extensively 
used  for  flooring,  stair  treads,  wainscoting,  tiling  and  for  sanitary 
kitchen,  laundry,  bathroom  and  hospital  finishing.  Many  installations 
have  been  made  in  large  public  buildings,  depots,  factories,  shops  and 
restaurants. 

The  prepared  materials,  ready  either  to  be  mixed  with  water  or 
with  magnesium  chloride  solution,  are  on  the  market  under  various 
trade  names.  Data  concerning  the  percentages  of  magnesium  chloride 
and  ground  magnesia  as  well  as  that  concerning  the  character  and 
quantity  of  filler  and  color  matter  added  are  naturally  guarded  as 
trade  secrets  by  the  manufacturers. 

Causes  of  occasional  unsatisfactory  installations  have  been  ascribed  ^ 
to  uncertain  climatic  changes,  lack  of  uniformity  of  the  mixtures  used, 
lack  of  care  in  handling  the  material,  deterioration  of  the  material 
through  exposure  either  before  or  after  mixing,  lack  of  experience  in 
laying,  etc.  Some  of  these  causes  could  probably  be  eliminated  by  the 
standardization  of  the  raw  material  used  and  of  acceptable  filler 
materials,  and  by  the  establishment  of  standard  proportions,  with 
benefit  to  the  industry  as  a  whole.  In  fact,  such  improvements  are 
being  made,  as  is  later  shown  herein  (see  pages  21-33,  inc.). 

For  cement  purposes  the  magnesite  when  burned  is  left  'caustic,' 
as  distinguished  from  'dead  burned'  magnesite,  and  contains  from 
2%  to  10%  CO,.  The  conditions  of  the  calcination  are  important  for 
the  same  material  will  undoubtedly  vary  greatly  in  its  reacting  prop- 
erties with  different  treatment  in  the  kiln.  The  magnesite  should  be 
comparatively  free  from  lime,  which  later  causes  swelling  in  the 
cement,  but  a  higher  silica  content,  up  to  12%,  is  not  objectionable, 
provided  the  association  of  the  silica  is  not  in  such  a  form  as  to  pre- 
vent proper  calcination  of  the  MgCOg. 

"When  properly  packed  in  paper-lined  casks,  barrels  or  boxes,  the 
material  is  fairly  permanent,  but  it  deteriorates  on  exposure.  It  can 
probably  be  kept  unopened  for  a  year  or  more  if  care  is  used,  but  it 
should  be  used  within  a  few  weeks  after  being  opened  even  under 
the  most  favorable  conditions. 

The  manufacture  of  magnesia  oxychloride  cement  products  is 
undoubtedly  a  promising  field  and  one  in  which  considerable  headway 
has  already"  been  made  in  this  state.  Calif ornian  magnesite  on  account 
of  its  exceptional  purity,  is  particularly  suitable  for  plastic  uses. 


•  For  a  detailed  account  of  investigations  into  the  uses  and  properties  of  magnesia 
cements,  see  : 

Eng.   Soc.  Western  Pennsylvania,  Proc.  1913,  vol.  29,  pp.  305-338,  418-444. 

U.  S.  Geol.  Sur.,  Mineral  Resources,  1913,  Part  II,  pp.  450-453. 

Cal.  State  Min.  Bur.,  Bulletin  74,  pp.  70-72,  1917,  contains  a  summary  of  the 
above-listed   papers. 


MAGNESITE   IN    CALIFORNIA.  19 

As  a  supply  af  magnesium  chloride  is  essential  to  the  plastic  magne- 
site  industry,  it  is  worthy  of  note,  here,  that  there  are  five  plants  at 
present  (May,  1925)  in  California  preparing  MgCU  from  the  residual 
bittern  water  of  salt-works  brines. 

Paper  Manufacture. 

For  some  years  previous  to  the  war  by  far  the  greater  part  of  the 
magnesite  mined  in  California  was  consumed  by  the  wood-pulp  paper 
mills  of  the  Pacific  Coast. 

In  what  is  known  as  the  sulphite  process  of  making  paper  from 
wood  pulp,  magnesium  bisulphite  has  been  found  to  be  one  of  the 
best  available  agents  for  the  digestion  of  the  wood  fiber.  The 
bisulphite  is  made  by  passing  sulphurous  fumes  through  calcined 
magnesite.  Calcium  and  sodium  bisulphite  can  also  be  used  but  cal- 
cium bisulphite  is  not  as  stable  as  magnesium  bisulphite  and  does 
not  give  as  good  results,  while  sodium  bisulphite,  although  better  than 
either  of  the  above,  is  too  expensive  for  general  use.  There  seems  to 
be  little  likelihood  of  aiw  substitute  displacing  magnesium  bisulphite 
in  this  process  and  the  paper  mills  will  no  doubt  continue  to  consume 
a  considerable  tonnage  of  magnesite  annually. 

Carbonic  Acid  Gas. 

Carbon  dioxide  (CO,)  or  carbonic  acid  gas  is  one  of  the  products 
given  off  during  the  calcining  of  magnesite.  This  gas  when  com- 
pressed into  liquid  form  in  steel  cylinders  (about  850  lb.  pressure) 
is  easily  transported  and  forms  an  article  of  considerable  commercial 
value.  It  is  used  by  bottlers  for  carbonating  soda-Avater  and  other 
beverages;  by  ice  plants  and  for  general  refrigerating  purposes  on 
ships  and  elsewhere. 

Formerly  about  1000  tons  of  crude  magnesite  was  annually  calcined 
by  San  Francisco  firms  for  the  manufacture  of  carbonic  acid  gas,  but 
of  late  years  they  have  obtained  the  gas  mostly  from  other  sources. 
During  the  war,  one  custom  calcining  plant  utilized  the  derived  carbon 
dioxide  and  sold  the  calcined  residue  to  paper  mills.  According  to 
reports  1  ton  of  magnesite  produces  about  500  lb.  of  gas,  when  finally 
compressed  into  liquid  form,  and  1200  lb.  of  calcined  magnesite  still 
carrying  some  20%  of  CO,.  At  most  calcining  plants,  however,  the 
gas  is  considered  simply  a  waste  product  and  allowed  to  escape. 

Miscellaneous  Applications. 

In  both  crude  and  calcined  form  magnesite  is  being  used  in  an 
increasing  number  of  ways.  Mixed  with  asbestos  it  is  used  as  a  heat- 
insulating  covering  for  steam-pipes  and  boilers.  It  is  said  to  be  used 
as  an  absorbent  in  the  manufacture  of  dynamite;  as  an  adulterant  in 
paints,  and  as  a  preventative  of  boiler  scale  where  sulphurous  water 
is  used.  It  is  also  used  for  making  damp-proof  and  fire-retarding 
mixtures.  Concrete  buildings  are  frequently  finished  with  a  coat  of 
magnesite  paint,  and  wood  and  burlap  protected  by  such  a  coating  are 
said  to  resist  fire  so  that  although  they  can  be  burned  by  the  direct 
application  of  a  fiame,  the  fire  will  not  spread  beyond  the  area  of 
contact. 


20  CALIFORNIA    STATE    MINING   BUREAU. 

Medicinal    Uses. 

Various  refined  magnesia  salts  are  used  for  medicinal  purposes  and 
in  toilet  preparations.  Among  these  are  epsom  salts  (magnesium  sul- 
phate), magnesia  alba  (basic  carbonate)  and  magnesium  chloride. 
These  salts  have  heretofore  been  imported  in  considerable  quantities 
from  Germany,  but  they  are  also  obtained  by  the  chemical  treatment 
of  magnesite.  Undoubtedly,  as  a  result  of  the  war  there  will  be  a 
large  increase  in  the  amount  of  refined  magnesia  salts  manufactured 
by  American  chemical  companies,  and  a  correspondingly  broader 
market  for  the  raw  materials. 

Metallic  Magnesium. 

Rather  important  developments  have  taken  place  since  1914,  looking 
toward  the  increased  production  of  the  metal  magnesium :  First,  as  a 
war  requisite;  and  second,  to  its  adaptation  to  other  useful  and  more 
desirable  purposes. 

Uses  which  involve  the  reduction  of  magnesium  metal  from  magnesite 
ores,  and  a  more  extensive  use  of  the  metal,  are  attracting  the  atten- 
tion of  producers.  Alloyed  with  steel,  magnesium  imparts  toughness 
to  the  former,  and  a  less  weight  is  required  for  a  given  strength.  It 
may  be  alloyed  with  aluminum;  and  it  is  claimed,  as  an  example,  that 
a  100-lb.  aluminum  automobile  body  costing  $20  could  be  displaced 
by  a  40-lb.  Al-Mg.  alloy  giving  the  same  strength  and  costing  the  same. 
It  is  said  that  the  metal  can  be  produced  for  50ff  per  lb.  by  a  plant 
at  Niagara  Falls.  An  alloy  of  magnesium  with  silver  is  said  to  make  a 
non-tarnishable  'silver.' 

F.  L.  Hess  ^  says : 

"Elemental  magnesium  is  known  to  comparatively  few  people  and  to  most  of 
those  few  chiefly  as  a  silvery  powder  of  low  specilic  gravity,  used  in  flash  lights 
for  photography ;  to  a  few  others  it  is  known  as  a  narrow  ribbon  or  as  a  fine 
granular  substance  ;  *  *  *  and  to  a  still  smaller  number  it  is  known  in  massive 
form.  It  seems  probable,  however,  that  magnesium  will  become  very  much  more 
common  and  it  may  become  as  common  as  aluminum. 

"Magnesium  as  it  is  now  isolated,  is  a  beautiful  silvery-white  metal.  It  com- 
monly becomes  coated  with  a  white  film  of  oxide  in  a  few  days  or  weeks ;  but 
several  manufacturers  have  said  that  they  have  segregated  magnesium  having  a 
purity  of  99.99  per  cent  or  more,  which  has  remained  untarnished  or  at  most  has 
shown  no  more  tarnish  than  aluminum  after  an  exposure  of  six  to  ten  months  in  the 
open  air.  It  is  readily  malleable  and  is  ductile  when  heated.  *  *  *  When 
ignited  in  air  magnesium  burns  with  an  intense  white  light  very  rich  in  actinic 
rays,  and  this  property  gives  it  its  value  in  photographic  work.  *  *  *  Magnesium 
is  the  lightest  of  the  metals  now  known  that  remains  comparatively  unaltered 
under  atmospheric  conditions.  Its  specific  gravity  (1.74)  is  only  two-thirds  that 
of  aluminum   (2. 58)   and  two-ninths  that  of  iron   (7.86)." 

Continuing,  he  says : 

"With  the  beginning  of  the  European  war  a  great  demand  sprang  up  for 
magnesium  to  be  used  in  the  unprecedentedly  large  quantities  of  war  materials 
manufactured,  but  the  supply,  not  only  of  the  metal  but  of  the  magnesium  chloride 
used  in  its  manufacture,  which  had  previously  come  from  Germany,  was  cut  off 
and  caused  the  embarkation  of  American  firms  in  the  business  of  isolating  the 
metal  from  minerals  of  domestic  production.  *  *  *  xhe  total  production  dur- 
ing the  year  1915  was  87,500  lbs.  valued  at  about  $440,000." 

The  metal  was  generally  produced  by  electrolytic  methods  from 
magnesium  chloride.  Part  of  this  was  imported  stock,  part  was 
obtained  from  the  bittern  waters  left  after  the  extraction  of  salt  from 
ocean  water  or  brines,  and  part  was  derived  from  California  magnesite. 

'  U.  S.  Geol.  Surv  :  Mineral  resources  of  the  U.  S.,   1915,  Part  I,  page  735. 


MAGNESITE   IN    CALIFORNIA.  21 

In  regard  to  the  uses  for  magnesium,  Iless  further^  writes: 

"The  largest  use  during  1915  was  in  the  making  of  war  munitions.  It  does 
not  enter  into  explosives  nor  into  arms  as  an  integral  part,  but  small  quantities 
are  put  in  shrapnel  shells  in  order  that  observers  and  gunners  may  know  exactly 
where  the  shells  are  bursting.  Bv  day  the  burning  magnesium  gives  a  dense, 
pure-white  cloud  of  magnesium  oxide,  that  can  be  readily  and  distinctly  seen,  and 
at  night  it  gives  a  dazzling  white  light.  Larger  quantities  are  u.sed  in  aerial 
bombs  and  rockets  used  for  lighting  up  the  country  at  night.  *  *  *  A  small 
quantity  of  magnesium  is  also  used  in  fireworks  for  peaceful  displays.  A  number 
of  tons  are  used  each  year  for  flash  lights  for  photographic  purposes.  *  *  * 
Magnesium  has  not  found  much  direct  use  as  a  metal,  but  magnalium,  an  alloy 
of  aluminum,  containing  2  rier  cent  or  less  of  magnesium  and  small  percentages 
of   other   metals,   is   said   to   be  used   in  automobiles   and   airplanes. 

"The  value  of  magnesium  as  a  deoxidizer  is  utilized  by  adding  it  to  monel  metal 
or  nickel  when  melted  for  casting.  It  has  been  used  in  steel  for  the  same  purpose 
but  has  so  far  not  displaced  aluminum  to  any  large  extent,  though  it  is  used  by  some 
steel  makers.     Small  quantities  are  used  in  chemistry.      «      *      * 

"Among  the  uses  of  magnesium  to  which  manufacturers  look  forward  are  its 
employment  to  replace  aluminum  as  a  deoxidizer  in  steel,  and  also  to  replace 
aluminum,  in  part,  in  automobiles  and  airplanes." 

Among  other  firms,  The  American  Magnesium  Corporation,  Niagara 
Falls,  N.  Y.,  now  offers,  according  to  current  trade  journal  advertise- 
ments, magnesium  bars — 99%  pure,  magnesium-aluminum  alloys, 
magnesium-silicon  alloys,  magnesium-copper  alloys,  and  magnesium 
powder^ 

In  view  of  the  great  variety,  the  recognized  utility,  and  the  sub- 
stantial value  of  the  products  obtained  from  the  mineral  magnesite  it 
seems  certain  that  the  deposits  in  California  must  continue  to  be  the 
center  of  much  interest,  not  only  to  those  directly  interested  in  magne- 
site mining,  but  to  a  large  portion  of  that  class  engaged  in  manufac- 
turing various  finished  products  from  the  raw  material,  who  from 
force  of  circumstances  or  by  preference,  wish  to  obtain  their  supplies 
from  domestic  sources. 

TESTING  AND  SPECIFICATIONS  FOR  MAGNESIUM 
OXYCHLORIDE  CEMENTS. 

Reliable  and  conclusive  testing  of  plastic  calcined  magnesite  has  long 
been  a  serious  problem  to  users  of  this  material.  Attempts  to  regulate 
quality  by  chemical  specifications  have  not  been  successful.  Unfortu- 
nately, it  has  been  found  that  much  poor  as  well  as  good  calcined  mag- 
nesite will  meet  many  of  such  chemical  specifications. 

"The  industry  in  general  is  coming  to  believe  that  a  specification  for  this 
product  should  be  written  on  the  basis  of  physical  tests  only,  with  entire  elimination 
of  chemical  analysis.  The  physical  tests  ordinarily  recommended  are  those  for 
fineness  of  calcined  magnesite,  and  for  strength,  constancy  of  volume,  setting  time, 
and  resistance  to  water  of  the  finished  cement.  Tests  of  this  nature  unquestionably 
furnish  valuable  information  as  to  the  quality  in  calcined  magnesite.  It  is  inter- 
esting to  compare  such  test  results  with  the  results  of  chemical  analysis  and 
particularly  to  search  for  special  analytical  determinations  which  might  throw  light 
on  the  question  of  quality  before  totally  abandoning  the  use  of  chemical  tests."  - 

According  to  Seaton.^ 

"The  chemist  has  long  known  that  the  magnesium  oxy-chlorides  were  decom- 
posed by  water,  with  the  formation  of  magnesium  chloride  in  solution  and  the 
precipitation  of  magnesium  hydrate.  By  many  this  fact  has  been  considered  to 
mean  that  oxy-chloride  cements  could  never  withstand  the  action  of  water  without 
serious  loss  in  cementing  properties  and  consequent  deterioration  in  structural  value 
of  any  material  in  which  oxy-chlorides  were  used.  Such  reasoning  is  fallacious. 
Certain  forms  of  magnesium  hydrate  closely  resemble  the  natural   mineral   bruclte, 


»Op.  cit.,  p.  740. 

-Seaton,  Hill  and  Stewart:  Chem.  &  Met.  Eng.,  Vol.  25,  Aug.  17,  1921. 
^  Seaton,  M.  Y.,  Magnesium  oxychloride  cements:  Chemical  Age,  Vol.   31,  pp.   17-2r 
Jan.  1923. 


22  CALIFORNIA    STATE    MINING   BUREAU. 

which  is  magnesium  hydroxide,  in  properties,  having  high  strength  and  excellent 
binding  power.  Fortunately,  it  is  to  these  forms  of  hydrate  that  oxy-chlorides 
revert  when  such  oxy-chlorides  are  of  proper  constitution  and  are  weathered  or 
wet  in  normal  fashion.  The  recollection  that  the  calcium  hydrate  in  lime  mortars 
is  slowly  transformed  to  calcium  carbonate  on  aging  should  be  sufficient  to  lay  at 
rest  the  fear  that  a  change  in  the  composition  of  a  cementing  material  need  neces- 
sarily result  in  structural  unsoundness. 

"The  solid  solution  which  always  constitutes  a  major  part  of  magnesium  oxy- 
chloride  cement  contains  a  considerable  amount  of  water.  Its  water  content  varies 
according  to  its  environment,  being  lower  as  temperature  rises  and  humidity  of 
the  air  drops,  and  higher  as  the  reverse  changes  take  place.  As  water  content  is 
reduced,  slight  shrinkage  of  the  oxy-chloride  results  while  slight  expansion  follows 
increase  in  water  content.  This  is  exceedingly  fortunate,  for  it  tends  to  counter- 
act the  normal  volume  changes  which  occur  through  temperature  change.  That 
is,  the  usual  expansion  with  rise  in  temperature  is,  with  the  oxy-chlorides,  coun- 
teracted, at  least  in  part,  by  the  shrinkage  caused  tlirough  loss  in  water  of  the 
basic  binding  material.  It  is  particularly  for  this  reason  that  the  oxy-chlorides 
have  the  name  of  being  remarkably  free  from  expansion  or  contraction  movements. 
******* 

"Specifications. 

"Consumers  of  plastic  calcined  magnesite  throughout  the  early  development  of  the 
industry  experienced  grave  difficulty  in  purchasing  a  product  of  satisfactory  cement- 
making  properties.  Plastic  calcined  magnesite  was  sold  wholly  on  analytical  specifica- 
tions, the  content  of  magnesium  oxide,  of  ignition  loss  and  of  lime  ordinarily 
being  kept  within  moderately  close  limits.  It  developed  that  magnesium  oxides 
of  identical  chemical  analysis  did  not  necessarily  have  comparable  cement-making 
value.  At  the  joint  instigation  of  tlie  world's  largest  oxy-chloride  producer  and 
of  the  largest  magnesium  chloride  producer  in  the  United  States  investigations 
were  undertaken  which  ended  in  showing  the  causes  for  the  discrepancies  pre- 
viously noted,  and  for  the  first  time  establisliing  the  industry  on  a  substantial  basis. 

"The  gypsum  and  the  Portland  cement  industries  have  definitely  established  that 
the  physical  character  and  cement-making  value  of  their  products  cannot  be  specified 
in  terms  of  chemical  analysis.  The  lime  industry  has  recently  found  the  same 
facts  to  hold  true  for  its  particular  field.  A  parallel  case  exists  in  plastic  calcined 
magnesite.  Laboratory  investigators  have  long  known  that  the  reactivity  of 
magnesium  oxide  was  largely  a  function  of  the  time-temperature  history  of  its 
calcination.  At  one  extreme  stands  the  active  oxide  first  formed  when  carbon 
dioxide  is  just  barely  removed  from  the  natural  carbonate,  while  at  the  other 
extreme  artificial  periclase  is  found.  This  is  still  magnesium  oxide,  but  shows 
no  ability  to  react  with  magnesium  chloride  solution  or  to  become  hydrated  In 
contact  with  water.  Neither  of  these  products  is  satisfactory  when  used  in  the 
preparation  oxy-chloride  or  Sorel  cements.  The  material  desired  lies  somewhere 
between  these  two  extremes.  Unfortunately,  there  are  as  yet  no  methods  which 
will  rapidly  identify  the  particular  oxide  which  the  oxy-chloride  industry  needs. 
Recourse  must  be  had  to  the  preparation  of  oxy-chloride  cements  and  the  exam- 
ination of  their  physical  properties.  In  other  words,  physical  tests  have  practi- 
cally wliolly  replaced  the  chemical  tests  once  relied  on,  and  it  is  through  such 
physical  tests  that  all  production  of  magnesite  should  be  guided. 

"Production. 

"Formerly  all  plastic  calcined  magnesite  was  prepared  in  stack  ot  upright 
kilns  of  the  type  of  the  familiar  vertical  lime-kiln,  and  such  kilns  still  persist  in 
some  California  operations,  although  their  product  can  never  approach  in  qu.ality 
the  material  obtained  from  other  types  of  furnaces.  If  a  magnesium  oxide  of  high 
quality  is  to  be  prepared,  time  and  temperature  of  calcination  must  be  held  within 
narrow  limits.  This  is  obviously  impossible  in  the  burning  of  lump  ore  in  a  stack 
kiln,  where  to  insure  heat  penetration  and  decarbonization  to  the  center  of  the 
lump  so  much  heat  must  be  supplied  that  the  outer  material  is  seriously  over-burned. 
For  production  of  high-quality  material  the  ore  must  be  sized  within  Quite  narrow 
limits,  and  a  kiln  or  furnace  adapted  for  burning  such  fine  ore  employed.  Up 
to  this  time,  because  of  the  temperature  involved,  the  rotary  kiln  only  has  been 
in  active  use.  The  Wedge  or  Herreshoff  furnace  may,  perhaps,  find  a  field  in  the 
treatment  of  the  higher-iron  ores,  which  calcine  at  a  low  temperature,  but  it  is 
doubtful  whether  they  will  withstand  the  temperatures  involved  in  the  treatment 
of  the  purer  ores,  which  must  be  heated  to  approximately  1,100°  C. 

"In  mining  operations  care  must  be  taken  to  hold  the  analysis  of  the  ore  delivered 
to  a  calcining  plant  within  quite  narrow  limits.  This  is  the  principal  place  in  the, 
magnesite  calcining  industry  where  chemical  analysis  is  of  vital  importance.  As 
calcium  carbonate  is  fairly  completely  decomposed  at  the  calcining  temperatures 
employed  and  as  the  resulting  calcium  oxide  is  exceedingly  injurious  to  the  oxy- 
chloride  reaction, 1  lime  content  must  be  held  at  a  low  figure.  Then,  too,  small 
amounts  of  certain  substances,  notably  iron,  and  to  a  lesser  extent  alumina  and 
silica,  influence  catalytically  the  reactions  which  occur  during  magnesite  calcining. 
If  they  are  present  in  quantity,  calcining  temperatures  must  be  lowered  materially 
to  avoid  over-burning.  These  impurities  are  not  injurious  in  the  sense  that  lime 
is,  but  ore  containing  them  must  be  kept  separate  from  ore  containing  no  such 
material  and   treated   in   individual  fashion   in   order  to  yield  a   satisfactory  product. 

"No  particular  comment  is  called  for  on  the  general  operations  of  mining  or  of 
crushing  the  ore  before  calcination.  In  practice  it  is  found  that  half-inch  sizing 
is  essential  if  the  appearance  of  either  over-burned  or  under-burned  materal  in 
the  finished  product  is  to  be   avoided.      Kiln   practice,   however,   is  essentially  differ- 


^  See   in   this   connection,    Seaton,    Hill   and   Stewart,   Chem.    &   Met.    Eng.,    Vol.    25, 
page  270. 


MAGNESITE   IN    CALIFORNIA.  23 

ent  from  that  common  in  either  the  cement  or  the  lime  industries,  although  it  is 
conceivable  that  the  lime  industry  will  some  day,  employ  the  methods  used  in  the 
preparation  of  calcined  magnesite.  In  the  operation  of  a  rotary  kiln  for  magnesite 
production  not  only  must  the  maximum  temperature  in  the  kiln  be  carefully  regu- 
lated, but  a  temperature  closely  approaching  the  maximum  must  be  maintained  over  a 
zone  of  considerable  length.  In  normal  practice  the  carbon  dioxide  is  expelled 
from  the  magnesite  at  a  temperature  much  below  that  necessary  for  the  develop- 
ment of  the  particular  type  of  magnesium  oxide  which  is  desired.  Gas  is  fairly 
well  liberated,  in  other  words,  before  the  ore  enters  the  zone  in  the  kiln  in  which 
definite  temperature  is  maintained.  It  is  the  length  of  this  zone,  its  temperature 
and  the  rate  of  passage  of  magnesite  down  the  kiln  which  determine  the  character 
of  the  calcined  product. 

♦  «****• 

"The  calcined  magnesite  must  be  ground  to  a  product  somewhat  finer  than 
ordinary  Portland  cement.  For  this  grinding  the  use  of  ball  or  tube  mills  is  not 
permissible,  because  of  the  packing  of  the  material  on  the  sides  of  .such  a  mill. 
The  ring  roll-mill  using  air  separation  or  the  burrstone  mill  give  excellent  products. 
For  this  particular  grinding  problem  the  old-fashioned  burr  mill,  which  has  fallen 
into  disrepute  in  many  industries,  is  particularly  adapted  and  gives  a  material 
diflficult  to  equal  by  any  other  type  of  mill. 

"The  finished  plastic  calcined  magnesite  is  a  fine  powder,  about  85  per  cent 
of  which  passes  a  200-mesh  screen.  It  varies  in  color  from  white  through  creams 
to  dark  browns  or  even  chocolates.  The  darker-colored  product  may  have  intrin- 
sically the  same  cement  making  properties  as  the  lighter  materials,  giving  only 
a  cement  of  darker  color,  and  consequently  limited  to  use  to  those  cases  where 
color  in  the  finished  product  is  no  object.  The  cream-colored  magnesite  may  give 
even  a  whiter  cement  than   the  pure  white  rhagnesite. 


"Raw  Materials — Magnesiuvi  Chloride. 

"Magnesium  chloride  is  also  an  essential  raw  material  for  the  industry.  The 
potash  deposits  in  the  Stassfurt  region  in  Germany  contain,  of  course,  enormous 
quantities  of  magnesium  chloride,  which  in  more  or  less  impure  form  is  a  waste 
product  from  potash  plants.  German  magnesium  chloride  was  for  many  years  the 
standard  of  the  industry  in  the  United  States,  but  particularly  since  the  war 
domestic  production  has  taken  the  place  of  first  importance. 

"Addition  of  Aaareaates. 

"The  remaining  raw  materials  of  Interest  to  the  industry  may  be  classed  under 
the  general  head  of  aggregates,  and  require  very  close  attention  by  operators 
producing  oxy-chloride  cements.  For  a  number  of  reasons  the  practice  of  assembl- 
ing mixes  at  the  point  where  they  are  to  be  applied — that  is,  adding  sand  and 
other  aggregates  to  the  magnesium  oxide  in  the  field — is  not  permissible.  In  the  first 
place,  only  dry  aggregates  can  be  used,  as  the  oxy-chloride  cements  are  very 
sensitive  to  variation  in  the  strength  of  magnesium  chloride  employed  in  their 
preparation.  If  wet  aggregates  are  used  it  is  impossible  to  make  proper  adjust- 
ment for  the  varying  amount  of  water  thus  introduced.  Furthernaore,  a  special 
knowledge   is  required  for  the  choice  of  satisfactory   aggregates. 

"Not  only  are  more  materials  needed  than  are  employed  in  concrete  or  gypsum 
plaster  practice,  where  sand  or  sand  and  stone  only  are  required,  but  the  requirements 
for  a  satisfactory  sand  are  quite  different  from  those  which  hold  in  the  prepara- 
tion of  high  quality  concrete.  If  sand  only  were  needed  in  oxy-chloride  cements, 
education  or  the  insistence  on  special  screening  methods  might  solve  the  difficulty. 
All  commercial  products,  however,  contain  a  fine  aggregate,  such  as  silex  or 
marbledust,  and  almost  invariably  a  fibrous  material  such  as  asbestos.  These 
materials,  of  standardized  quality,  are  not  available  locally  at  the  points  where 
such  cements  are  used.  An  even  more  vital  factor  in  eliminating  the  possibility 
of  field-prepared  mixes  is  the  fact  that  the  principles  of  oxy-chloride  mix  forma- 
tion are  perhaps  more  complicated  than  those  which  hold  for  concretes.  Mix 
balance  is  not  improved  by  adding  more  magnesite  as  a  factor  of  safety  to  take  care 
of  inferior  aggregates,  as  can  be  done  with  Portland  cement  in  concrete  work. 
Instead,  the  quality  of  an  oxy-chloride  mix  is  deteriorated  if  either  too  much  or  too 
little  magnesium  oxide  is  employed,  and  for  best  results  the  quantity  of  oxide 
used  must  be  carefully  regulated  to  the  characteristics  of  the  other  materials  used 
in  the  mix.  For  this  reason  factory  prepared  mixes  are  the  standards  in  the 
oxy-chloride  industry,  and  despite  the  disadvantages  of  such  mixes  in  somewhat 
higher  cost  for  transportation  there  is  little  likelihood  of  the  use  of  field  prepared 
mixes  gaining  in  favor. 

"The  most  fundamental  principle  involved  in  the  formation  of  suitable  oxy- 
chloride  mixes  may  be  described  as  the  'thin  glue  joint'  principle.  It  is  common 
knowledge  -that  in  gluing  two  pieces  of  wood  best  mechanical  properties,  are 
obtained  when  the  glue  film  interposed  between  the  two  wood  surfaces  is  of  minimum 
thickness.  Exactly  the  same  principle  holds  for  oxy-chlotide  mixes.  TJie  magnesium 
oxide-magnesium  "chloride  mix  which  eventually  gives  an  oxy-chloride  of  some 
indefinite  composition  should  be  considered  as  a  mineral  glue  which  will  function 
to  best  advantage  only  when  it  is  present  as  thin  films  between  closely  packed 
particles  of  aggregate.  Because  the  reaction  between  magnesium  oxide  and  chloride 
is  almost  totally  complete,  without  the  surface  reaction  effect  which  exists  between 
Portland  cement  particles  and  water,  it  is  necessary  to  supply  fine  aggregate  to 
partially  fill  the  voids  between  the  coarser  sand  particles.  If  this  is  not  done, 
so  large  a  volume  of  oxy-chloride  cement  appears  between  sand  grains  that  the  thin 


24  CALIFORNIA    STATE    MINING   BUREAU. 

glue  jfjint  principle  is  violated  and  weakness  results.  It  is  obvious  that  in  follow- 
ing out  this  principle  a  mix  of  high  density  is  unavoidably  obtained. 

'•Oxv-chloride  cements  are  finally  used  in  by  far  the  majority  of  cases  by  work- 
men of  only  ordinary  skill,  who  in  most  instances  handle  the  plastic  cement  with 
trowels  or  similar  tools.  It  is  obvious  that  such  a  worker  will  obtain  best  mechanical 
results  if  the  mix  he  works  with  is  easy  to  handle  and  can  be  applied  with  only 
normal  effort.  For  this  reason  attention  is  given  by  oxy-chloride  manufacturers 
to  the  production  of  high  plasticity  in  their  finished  materials.  This  is  usually 
done  through  the  addition  of  asbestos  or  a  related  fibrous  material.  Fortunately, 
as  will  be  later  shown,  such  an  addition  is  permissible  here,  and  the  change  in 
ratio  of  liquid  to  solid  resulting  is  not  detrimental,  as  it  is  in  Portland  cement 
Dr3.ctic6- 

"Of  vital  importance  too  in  the  preparation  of  oxy-chloride  cements  is  the 
question  of  the  strength  of  the  magnesium  chloride  solution  employed.  General 
experience  has  indicated  that  a  solution  of  a  gravity  of  22°  Baume  gives  best 
results,  and  that  if  this  strength  is  greatly  departed  from  trouble  will  result." 

The  same  writer  further  states  ^ 

"The  fundamental  point  back  of  the  adoption  of  physical  tests  of  quality  criteria 
for  calcined  magnesite  lies  in  the  observation  that  magnesium  oxide  may  exist  in 
different  forms,  which,  although  they  show  the  same  chemical  analysis,  behave 
entirely  differently  in  the  oxy-chloride  reaction,  and  give  cements  of  widely  varying 
character.  They  range  from  the  exceedingly  active  oxide,  showing  rapid  reaction 
with  magnesium  chloride  but  giving  a  cement  of  undesirable  properties,  which  is 
first  formed  on  heating  natural  magnesite,  to  the  wholly  inactive  periclase  which 
results  from  burning  at  high  temperatvires.  While  'dead  burn'  magnesia  is  desired 
by  the  refractory  user,  it  is  useless  to  an  oxy-chloride  producer.  Although  much 
thought  has  l^een  given  to  the  question  of  the  constitution  of  these  different  oxides, 
and  although  they  have  been  examined  by  every  modern  method  known  to  the 
chemist  and  the  physicist,  we  are  still  without  any  too  definite  knowledge  of  their 
constitution,   and  without  quantitative  method  for  their  determination. 

"While  there  is  now  quite  universal  recognition  of  the  value  of  physical  tests  in 
the  examination  of  magnesites,  there  is  still  some  difference  of  opinion  as  to  the 
part  which  chemical  analysis  should  play  in  the  industry.  From  the  purchaser's 
standpoint,  it  may  be  positively  concluded  that  analytical  determinations  will  give 
no  useful  index  of  the  value  of  plastic  magnesia.  The  most  common  argument 
of  the  analyst  is  that  a  magnesite  containing  9090  of  magnesium  oxide  should 
be  considerably  better  than  one  containing  70%  magnesium  oxide.  If  the  chemist's 
determination  could  indicate  the  reactive  content  of  magnesium  oxide,  this  would  be 
the  case,  but  it  is  entirely  possible  that  a  70%  MgO  material  may  contain  more 
active  magnesium  oxide  per  unit  weight  than  the  material  showing  an  analysis 
of  90%. 

iii  iii  *  *  *  ^  ^ 

"If  the  worth  of  a  calcined  magnesite  is  to  be  judged  from  the  physical  properties 
of  an  oxv-chloride  mix  in  which  the  magnesite  is  used,  it  is  essential  that  the  char- 
acter and  gradation  of  the  other  ingredients  used  in  the  testing  mix  must  from  a 
practical  standpoint,  be  kept  constant  at  all  times.  A  mix  subscribed  to  some 
time  ago  bv  a  committee  of  the  producers  of  domestic  magnesite,  (including  repre- 
sentatives from  the  U.  S.  Bureau  of  Standards  and  U.  S.  Bureau  of  Mines)  has. 
to  the  best  of  our  knowledge,  not  been  materially  bettered  by  any  subsequent 
work.  It  follows,  in  make-up,  the  principles  which  have  proven  themselves  sound 
in  extensive  field  practice.  It  is  composed  of  ingredients  easy  to  obtain  in  any 
locality,  and  gives  a  mix  of  normal,  well  balanced  properties.  It  contains  five 
parts  of  Standard  Ottawa  Sand,  screened  between  20  and  30  meshes ;  two  parts 
of  Silex  or  Ground  Silica,  which  practically  completely  passes  a  100-mesh  screen 
and  shows  about  75%  passing  a  200-mesh  screen;  and  one  part  of  the  calcined 
magnesite  under  test.  With  this  mix  a  solution  of  magnesium  chloride  of  a 
gravity  of  22°  Baume  is  used,  such  solution  being  prepared  from  a  magnesium 
chloride  showing  not  over  2%  of  magnesium  sulphate,  2%  of  calcium  chloride,  or 
2%  of  salt,  on  a  fused  magnesium  chloride  basis.  This  solution  is  added  to  the 
well  mixed  dry  ingredients  until  a  mortar  is  obtained  of  such  consistency  that  it 
will  just  support  a  flat-ended  metal  cylinder  one  inch  in  diameter  and  weighing 
250  grams.  Specimens  made  of  such  mixes  are  then  subjected  to  various  tests  to 
establish  various  values  of  the  magnesium  oxide  as  a  cementing  medium.  The 
results  obtained  from  examination  of  magnesites  by  use  of  such  a  mix  have  been 
invaluable  both  from  a  consumer's  and  producer's  standpoint. 
******* 

"Tests  of  the  setting  time  of  a  calcined  magnesite  are  almost  invariably  required. 
It  is  necessary  to  employ  the  standard  testing  mix  for  this  determination,  just 
as  for  the  determination  of  physical  strength,  for  the  setting  time  of  a  neat 
mixture  of  magnesite  and  magnesium  chloride  bears  little  relation  to  the  beha.vior 
which  this  same  magnesite  exhibits  in  the  complex  mixes  in  which  it  is  ordinarily 
employed.  On  mortars  of  the  testing  mix,  setting  time  may  be  determined  by  use 
of  standard  Gilmore  needles.  The  Vicat  needle  is  not  applicable  because  of  the 
coarseness  of  the  mix.  Care  must  be  taken  in  examining  the  impressions  made 
by  the  Gilmore  needles,  as  the  marks  are  by  no  means  as  sharp  and  distinct  as  they 
are  on  the  fine  grained  pats  of  neat  Portland  cement  usually  tested. 

"There  is  probably  no  property  of  plastic  calcined  magnesite  which  is  more  mis- 
understood   or    is   the'   subject   of   more   disputes   than   is   that   of   its    time   of   set.      It 


1  Seaton,  M.  Y.,  Magnesite  testing  practice  :  Pamphlet  issued  by  the  Sierra  Magne- 
,site  Company,  1923. 


MAGNESITE   IN    CALIFORNIA.  25 

is  not  generally  recognized  that  temperature  of  tlie  atmosphere  at  the  point  where 
an  oxv-chloride  mix  is  applied  exerts  an  enormous  effect  on  setting  time.  The 
same  product  which  might  meet  a  customer's  requirements  exactly  under  moderate 
atmospheric  conditions,  would  perhaps  prove  far  too  fast  setting  during  extreme 
summer  weatlier,  or  far  too  slow  setting  in  cool  damp  weather.  The  setting  time 
of  an  oxy-chloride  mix  is  roughly  reduced  to  half  its  original  value  when  temperature 
rises  fiom  the  normal  70°  at  which  most  tests  are  specified,  to  100°,  while  the 
time  for  .set  is  doubled  if  the  temperature  drops  from  70°  to  50°.  Humidity  also 
exerts  a  pronounced  effect  on  setting  time,  high  humidity  increasing  time  of  set, 
and  low  humidity  reducing  it.  Perhaps  more  important  still  is  the  effect  which 
change  in  the  character  of  tlie  commercial  mix  in  which  the  magnesite  is  used 
exerts.  Thus,  a  mix  higli  in  asbestos  and  wood  flour  may  require  from  one  and  a 
half  to  four  times  as  long  for  setting  as  does  the  standard  testing  mix,  while  on 
the  other  hand  a  high  magnesite  percentage  flooring,  particularly  of  the  mineral 
type,  may  set  faster  than  the  standard  testing  mix.  Magnesite  consumers  should 
realize  tliat.  constant  setting  time  can  never  be  secured  unless  temperature  is  held 
constant  and  if  no  material  change  i-s  made  in  the  character  of  mix  employed.  A 
surprising  difference  in  time  of  set  is  noted  by  so  common  and  unappreciated  a 
change  in  mix  characteristic  as  a  variation  in  the  grading  of  silicas  or  other  aggre- 
gate. Then  too,  variations  in  the  time  of  reaction  or  set  is  occasioned  by  the  time 
that  may  lapse  between  the  time  the  magnesite  is  calcined  and  the  time  it  is 
used.  Generally,  freshly  calcined  magnesite  reacts  more  rapidly  than  magnesite  that 
has  been  stored  for  a   considerable  period   of  time. 

******* 

"It  should  be  realized  that  oxy-chloride  products  in  well  over  95%  of  the  cases 
in  which  they  are  used  are  employed  in  the  form  of  thin  layers  applied  either  to 
floor  or  to  wall  surfaces.  Up  to  the  present  time,  they  have  not  yet  been  used  in 
mass  work,  sucli  as  Portland  cement  concrete  is.  All  successful  oxy-chloride  prac- 
tice in  the  field  involves  tlie  free  exposure  of  thin  layers  of  the  product  to  the  cir- 
culating and  drying  influence  of  the  atmosphere.  Probably  the  main  reason  that 
oxy-chloride  strength  tests  in  most  instances  have  failed  to  give  a  true  index  of 
the  character  of  the  product  is  because  an  attempt  has  been  made  to  apply  to 
oxy-chloride  mixes  the  methods  ordinarily  employed  in  the  testing  of  Portland  cement. 
These  methods  are  designed  for  use  on  a  material  of  radically  different  charac- 
teristics from  the  oxy-chlorides.  All  of  the  major  uses  of  concrete  involve  its 
application  in  masses  of  considerable  dimensions,  and  it  is  aged  either  under  water 
or  in  moist  atmosphere.  Concrete  design  is  drawn  so  that  concrete  must  resist 
compressive  stresses  only.  In  fact,  in  the  ordinary  calculations,  the  tensile  strength 
of  concrete  is  not  allowed  for.  although  tension  tests  of  concrete  mortars  are  still 
made,  test  pieces  being  in  the  form  of  the  well  known  briquettes,  which  are  aged 
under  water  for  seven  or  twenty-eight  days.  *  *  *  Neither  tensile  briquettes 
nor  compression  cubes  or  cylinders  can  be  aged  under  exposure  conditions  even 
approximating  those  existing  in  oxy-chloride  field  work,  particularly  during  their 
early  age,  when  surface  evaporation  is  of  paramount  importance, 

"It  is  not  generally  recognized  that  conditions  of  temperature  and  humidity  of  the 
atmosphere  in  which  oxy-chloride  test  pieces  are  made  and  stored  exert  an 
enormous  influence  on  the  results  obtained.  In  cement  testing  practice,  an 
artificial  atmosphere  saturated  with  water  is  maintained,  or  test  pieces  are  actually 
immersed  in  water,  for  the  reason  that  Portland  cement  is  essentially  a  hydraulic 
material.  Oxy-chloride  cement  is  not  a  hydraulic  cement  and  it  will  not  set  under 
these  circumstances.  Consequently,  oxy-chloride  cements,  in  order  to  set,  must 
he  exposed  to  the  air,  which  may  vary  greatly  in  properties.  Accordingly,  an  opera- 
tor may  make  tests  of  an  identical  mix  on  two  different  days  on  which  temperature 
differs  perhaps  20°  and  humidity  30  or  40  points,  and  be  surprised  because  duplicate 
values  are  not  obtained.  As  a  matter  of  fact,  he  should  be  more  surprised  if  his 
values  did  approach  each  other,  for  they  actually  should  differ  considerably  under 
such   circumstances. 

"Sound  testing  practice  for  determination  of  the  strength  of  oxy-chloride  cements 
involves  first,  the  use  of  test  pieces  which  can  be  aged  under  conditions  approxi- 
mating those  that  exist  in  the  field  application  of  oxy-chloride  products  ;  and  second, 
the  regulation  of  temperature  and  humidit;^  conditions  in  the  atmosphere  of  the 
testing  laboratories  within  quite  narrow  limits.  The  first  of  those  requirements  can 
be  met  by  preparing  test  pieces,  in  the  form  of  flat  bars,  not  over  one-half  inch 
in  thickness,  which  are  allowed  free  exposure  to  the  air  and  which  can  be  tested 
for  strength  by  breaking  in  a  cross-bending  machine  of  any  simple  design.  Com- 
parison of  tests  made  in  this  fashion  with  briquette  tests  on  the  same  mixes  made 
at  the  same  time  shows  that  there  is  little  relation  between  the  values  obtained. 
Depending  on  the  type  of  mix  and  the  character  of  magnesite  employed,  the  ratio 
between  a  cross-bending  test  of  thin  flat  bars  and  the  ordinary  briquette  test  varies 
between  1.5  and  3.2.  Such  a  variation  is  the  best  po.ssible  argument  for  the  adoption 
of  one  only  of  these  tests  as  a  standard.  Inasmuch  as  it  is  obvious  that  the  flat 
bar  is  aged  far  more  nearly  under  the  same  conditions  which  exist  in  the  field  than 
is  the  briquette,  the  bar  test  is  preferable  for  all  work  in  checking  oxy-chloride 
quality.  In  order  that  the  respective  values  of  different  magnesites  may  be  deter- 
mined, the  same  kinds  of  series  of  tests,  with  the  same  kind  of  apparatus  and  con- 
ducted under  nearly  equal  atmospheric  conditions  should  be  adopted.  Otherwise  the 
determinations  of  one  laboratory  will  not  even  approximate  the  findings  of  another. 
******* 

"The  question  of  the  minimum  strength  permissible  in  a  given  magnesite  when 
made  into  the  standard  mix  is  a  somewhat  difllcult  one.  To  obtain  thoroughly 
desirable  properties  in  all  respects  the  magnesite  producer  almost  invariably  finds 
it  necessary  to  make  moderate  concessions  from  the  strength  that  it  is  possible 
to  produce.  The  fact  is  that  in  most  cases  far  too  much  importance  is  attached  to 
high  early  strengths.     A  product  showing  a  modulus  of  rupture  In  crosg-bending  of 


26  CALIFORNIA    STATE    MINING   BUREAU. 

400  pounds  at  one  day,  900  pounds  at  seven  days,  and  1250  pounds  at  thirty  days, 
undoubtedly  has  ample  strength  to  meet  all  practical  requirements  of  the  industry. 
One  of  the  most  serious  mistakes  which  appears  in  past  and  current  oxy-chloride 
practice  is  the  idea  that  high  strength  is  a  criterion  of  quality  in  a  calcined  magne- 
site.  High  strength  is  obviously  an  advantage,  but  it  is  frequently  not  recognized 
that  a  material  may  have  enormous  strength  and  yet  be  so  deficient  in  the  other 
properties  whicli  are  required  for  satisfactory  field  practice  as  to  be  next  to  valueless. 
Too  many  operators  draw  tlieir  conclusions  as  to  magnesite  quality  from 
strengtli  tests  alone,  and  thus  seriously  mislead  themselves  on  the  quality  question. 
Of  two  products,  one  showing  1000  pounds  cross-bending  strengtli  at  fourteen  days 
and  increasing  this  strength  50%  after  prolonged  contact  with  water,  and  another 
showing  a  strength  of  2000  pounds  but  losing  two-thirds  of  this  strength  after 
the  same  water  contact,  there  can  be  little  doubt  as  to  which  is  superior. 

"This  last  example  brings  us  logically  to  the  ciuestion  of  water  resistance  tests 
of  oxy-chloride  mixes  as  a  factor  in  determination  of  magnesite  quality  Essentially 
all  oxy-chloride  products  used  for  stucco  or  flooring  work  are  subject  to  periodic 
contact  with  water.  Good  water  resistance  is  also  desirable  in  magnesite  used 
for  interior  plaster.  It  has  only  been  realized  comparatively  recently  that  the 
marked  difference  in  behavior  of  oxy-chloride  floorings,  stuccos  or  other  products 
with  reference  to  their  ability  to  witlistand  water  and  dampness  is  a  function  of  the 
quality  of  the  calcined  magnesite  employed  more  than  it  is  of  any  other  single 
factor.  The  literature  yields  many  instances  of  wide  variation  in  the  water 
resistance  of  oxy-chloride  products,  some  authors  stating  that  such  materials 
disintegrate  rapidly  in  contact  even  with  damp  air,  while  others  maintain  that  they 
withstand  water  perfectly.  These  discrepancies  are  explained  when  it  is  realized 
that  different  investigators  have  worked  with  different  calcined  magnesites,  and 
that  these  products  can  readily  introduce  as  great  differences  in  behavior  as  those 
recorded.  It  is  felt,  accordingly,  that  a  test  for  water  resistance  is  vitally  essential 
in  the  determination  of  the  value  of  any  calcined  magnesite. 

"Some  misconception  exists  as  to  the  permissible  methods  of  making  water 
resistance  tests.  Tests  are  frequently  reported  in  which  an  oxy-chloride  test 
piece  of  some  description  is  immersed  in  a  small  volume  of  water  and  allowed  to 
remain  for  a  considerable  period,  tlien  removed  and  tested.  Such  conditions  are 
very  far  removed  from  the  circumstances  to  which  any  oxy-chloride  product  is 
normally  subjected  in  the  field.  Steam  and  boiling  experiments  are  also  sometimes 
vaguely  applied.     Practical  value  comparisons  can  not  be  obtained  from  such  'stunts.' 

"Care  is  also  taken  in  the  installation  of  oxy-chloride  materials  to  insure  ample 
drainage  of  wall  or  floor,  and  it  is  pointed  out  by  all  operators  that  arrangements 
for  such  drainage  are  essential  if  successful  results  are  to  be  obtained.  Experiment 
shows  that  when  test  pieces  are  immersed  in  still  or  stagnant  water,  this  water 
extracts  a  certain  portion  of  the  magnesium  chloride  from  the  oxy-chloride  cement, 
thus  itself  becoming  a  solution  of  magnesium  chloride.  The  test,  therefore,  soon 
becomes  that  of  immersion  of  a  oxy-chloride  specimen  in  a  magnesium  chloride  solu- 
tion rather  than  immersion  in  water.  Magnesium  chloride  solutions  exert  a 
disastrous  disintegrating  effect  on  oxy-chloride  cements,  and  it  is  easy  to  see, 
accordingly,  how  an  improperly  applied  water  resistence  test  can  hardly  fail  to 
give  misleading  information.  Proper  procedure  involves  either  the  immersion  of  test 
pieces  in  circulating  clear  water,  or  more  correctly,  their  subjection  to  fine  water 
spray.  This  latter  procedure  more  closely  parallels  service  conditions,  particularly 
for  the  stucco  industry,  which  is  specially  interested  in  water  resistance  tests.  A 
procedure  which  has  been  found  particularly  valuable,  also  recommended  by  the 
magnesite  producers  committee  before  referred  to,  is  that  of  aging  flat  bars  for  a 
period  of  fourten  days,  spraying  two-thirds  of  the  specimens  for  three  twenty-four- 
hour  periods  with  intervening  twenty-four-hour  drying  periods,  breaking  half  of 
the  sprayed  specimens  wet,  redrying  the  other  half  two  days  and  then  breaking, 
and  at  the  same  time  breaking  the  original  third  of  the  specimens  which  have  not 
been  treated  with  water.  Results  can  be  recorded  as  dry  strengths,  wet  strengths 
and  recovered  strengths.  E.xperience  has  shown  that  for  a  material  of  high  quality 
tested  under  these  conditions,  wet  strength  should  be  at  least  50%  of  dry  strength, 
and  recovered  strength  90%  or  better  of  dry  strength.  In  fact,  the  Sierra  Magnesite 
Company  has  found  it  possible  to  consistently  produce  a  material  showing  a 
recovered  strength  under  these  conditions  of  100%  to  150%  of  dry  strength. 
******* 

"Tests  for  warping,  buckling,  expanding  and  contracting  properties  of  a  calcined 
magnesite  by  use  of  the  standard  testing  mix  also  furnish  valuable  information 
as  to  its  properties,  although  there  are  no  tests  which  are  more  difficult  to  inter- 
pret than  these.  The  test  itself  is  comparatively  simple  to  make.  Flat  bars  of  the 
oxy-chloride  mix  about  one-half  inch  thick,  two  inches  wide  and  some  twelve  inches 
long,  prepared  on  waxed  paper  so  that  their  movement  is  totally  unrestrained, 
can  have  inserted  into  their  upper  surface  while  they  are  still  soft  two  metal  clips 
carrying  punch  marks,  which  are  set  approximately  ten  inches  apart  by  aid  of 
the  reference  bar  accompanying  the  usual  Berry  strain  gauge.  Measurement  of  the 
position  of  these  punch  marks  is  then  taken  at  the  period  of  initial  set,  by  the 
Berry  gauge,  and  the  movement  of  the  bar  as  reflected  by  the  changed  position 
of  these  reference  points  measured  from  tima  to  time  with  the  instrument  in  ques- 
tion, readings  being  made  to  one-ten-thousandth  of  an  inch. 

"Another  dangerous  property  of  certain  magnesite,  observable  through  expansion 
measurements,  is  tlie  property  which  some  such  materials  possess  of  expanding 
radically  when  exposed  to  moist  air.  Instances  of  failure  of  composition  floors 
by  buckling  have  in  some  instances  been  traced  to  this  property  in  the  calcined 
magnesite  used.  Fortunately,  however,  it  is  found  that  materials  of  high  water 
resistance  do  not  exhibit  this  behavior,  and  accordingly  if  a  material  is  satisfactory 
in  the  water  resistance  test  the  added  time  and  trouble  of  making  an  expansion 
test  in  moist  air  is  not  always  considered  necessary. 


MAGNESITE   IN    CALIFORNIA.  27 

"Many  other  tests  of  lesser  importance  than  the  ones  previously  enumerated  are 
made  on  occasion  on  samples  of  calcined  maenesite,  using  the  standard  oxy-chloride 
testing  mix  previously  described.  Of  these  miscellaneous  tests,  the  one  most  com- 
monly made  is  probably  the  test  for  water  absorption  of  a  specimen,  frequently 
carried  out  by  immersing  the  sample  in  water  for  an  extended  period,  and  com- 
paring its  wet  weight  with  the  dry  weight  of  the  same  piece.  A  test  of  this  kind  is 
subject  to  grave  error,  because  of  the  fact  that  ihe  oxy-chloride  themselves  take 
on  water  of  constitution  when  treated  in  this  fashion,  and  gain  of  weight  is  always 
found,  even  though  the  theoretical  idea  of  complete  freedom  from  pores  or  voids 
could   be   reached. 

"The  wide  influence  of  mix  character  on  oxy-chloride  tests  has  been  previously 
mentioned,  particularly  in  the  discussion  of  setting  time.  Mix  constitution  affects 
all  the  properties  ordinarilv  determined  just  as  radically  as  it  does  the  rate  of 
set.  The  per  cent  of  asbestos  or  fibrous  material,  the  fineness  and  general  char- 
acter of  the  fine  aggregate  employed,  fineness  to  which  magnesite  is  ground,  the 
shape  and  size  of  the  sand  particles,  all  influence  strength,  water  resistance, 
expansion  and  contraction,  and  in  fact  nearly  all  the  physical  properties  of  a  mix. 
Although  the  character  of  a  calcined  magnesite  is  probably  the  most  vital  factor 
in  determining  the  character  of  any  oxy-chloride  mix,  it  should  be  thoroughly 
understood  that  even  the  use  of  a  calcined  magnesite  of  ideal  properties  will  not 
insure  the  obtaining  of  good  field  results  from  a  mix  unless  the  ingredients  employed 
are  of  proper  character  and  unless  they  are  used  in  such  proportions  as  to  allow 
of  the  satisfactory  development  of  the  necessary  strength,  ability  to  withstand  water, 
and  other  factors.      •      *      * 

"Illusion  Xo.   1 — The  High  Strength  Fallacy. 

"Judging  magnesite  quality  by  breaking  strength  tests,  an  almost  universal 
misconception,  is  not  only  an  erroneous  practice,  but  it  is  also  dangerously  mislead- 
ing. Any  reasonably  good  grade  of  crude  magnesite  ore,  can  be  calcined  in  such 
a  manner  that  cements  attaining  amazingly  high  strength  may  be  made  with  it. 
However,  careful  study  and  field  observations  have  conclusively  proven  that  a  great 
many  magnesites  which  have  exhibited  abnormally  high  breaking  strengths,  have 
failed  miserably  when  subjected  to  routine  service  conditions  for  which  such 
products  were  intended. 

"Strength  limits  assuring  reasonable  factors  of  safety  are,  of  course,  indispensable. 
But  it  is  of  far  greater  importance  that  certain  other  elements  in  magnesite, 
depending  upon  their  effect  on  the  worth  of  the  finished  product,  be  developed  or 
controlled. 

"Illusion  No.  2 — Purchasing  by  Sample. 

"Up  to  the  present  time,  few  if  any  manufacturers  of  oxy-chloride  materials 
have  specialized  on  magnesite  testing  to  the  extent  that  their  findings  can  be 
considered  as  accurate  as  the  determinations  arrived  at  by  technical  bureaus  which 
handle  this  particular  line  of  work  continuously  and  exclusively. 

"Before  deciding  to  purchase  magnesite,  users  in  most  cases  indicate  a  desire 
to  test  a  sample  of  the  magnesite  offered.  Such  tests  in  many  instances  intro- 
duce an  element  of  false  security,  for  the  reason  that  an  elementary  study  of  a 
sample  is  no  indication  of  the  character  or  uniformity  of  the  magnesite  the  seller 
may  later  be  able  to  deliver. 

"For  the  average  manufacturer  who  does  not  maintain  a  fully  organized  labora- 
tory and  technical  staff,  we  have  to  suggest  that  it  will  be  more  advantageous  to 
apply  such  practical  considerations  as  are  below  noted  in  an  effort  to  form  an 
opinion  of  magnesite  quality,  rather  than  to  depend  upon  rudimentary  observations 
of  a  sample   lot  of  material. 

"1.  Investigate  the  producer's  reputation,  his  organization,  his  record  for  fair 
dealing  and   his  financial  responsibility. 

"2.  Learn  through  reliable  sources  the  quality  of  the  crude  ore  contained  in  his 
deposits.  Ascertain  the  location  and  extent  of  his  ore  reserves.  Also  their  accessi- 
bility to  transportation  in  order  that  you  may  know  that  uninterrupted  deliveries 
and  efficient  service  will  be  assured  throughout  every  month  in  the  year. 

"3.  Satisfy  yourself  concerning  the  experience  and  responsibility  of  those  in 
charge  of  plant  and  laboratory  facilities,  for  upon  them  scientific  and  accurate 
control   and  production   processes   is    dependent. 

"Hakeem,  the  wise  man  of  Bagdad,  once  said  'The  priceless  ingredient  of  every 
product  is  the  honor  and  integrity  of  him  who  makes  it ;  consider  his  name  before 
you  buy.' 

"These  things  are  of  more  importance  in  deciding  upon  entering  into  a  contract 
for  the  purchase  of  magnesite  than  examination  of  samples  that  may  be  submitted. 
If  you  learn  through  personal  investigation  that  a  producer  of  calcined  magnesite 
employs  scientific,  intelligent  production  methods,  it  creates  confidence  in  that 
producer  and  his  product." 

The  effect  of  lime  in  calcined  magnesite  has  always  been  considered 
deleterious ;  but  apparently  the  form  in  which  it  occurs  is  important. 

"Inert  and  Active  Lime. 

"From  the  start  some  distinctioji  as  to  the  form  In  which  the  lime  occurs  must 
be  made.  In  many  oxy-chloride  cement  mixes  marble  dust  or  limestone  powder  is 
deliberately  used  as  an  aggregate  without  exerting  any  harmful  Influence  on  the 
properties  of  the  cement.  Such  forms  of  calcium  carbonate  act  merely  as  inert 
material,   their   effect   on   the   character   of  the   cement   being   roughly   equivalent   to 


28  CALIFORNIA    STATE    MINING   BUREAU. 

that  of  a  fine  sand  or  ground  silica  of  equal  fineness.  The  report  of  the  presence 
of  a  definite  amount  of  lime  in  a  calcined  magnesite  is  accordingly  meaningless 
unless  the  form  in  which  it  occurs  be  also  specified.  It  is  well  established  that 
addition  of  calcium  oxide  or  hydroxide  to  an  oxychloride  mix  markedly  diminishes 
its  strength.  Lime  in  this  form  or,  more  exactly,  any  form  of  lime  which  exerts 
an  injurious  effect  on  the  quality  of  an  oxychloride  can  well  be  designated  as 
'active  lime,'  and  it  would  be  expected  that  a  determination  of  the  content  of  lime 
of  tliis  character  would  be  of  considerable   value. 

"The  reduction  in  strength  caused  by  addition  of  lime  to  oxychloride  cements 
has  been  mentioned  by  several  writers  *  *  *.  If  the  magnesite  was  burned  at 
a  temperature  exceeding  1000  deg.  C,  the  lime  was  slowly  and  incompletely  dis- 
solved, but  magnesites  burned  at  lower  temperatures  gave  good  results. 

4e  ;f;  3)c  -K-  ,{:  4:  ,ie 

"Summary. 

"Methods  for  determination  of  'free'  and  of  'active'  lime  in  plastic  calcined 
magnesites  have  been  indicated,  and  the  distinction  between  total  lime  and  active 
lime  in  such  material  brought  out. 

"A  relation  between  active  lime  content  of  calcined  magnesites  and  physical 
properties    of    the   oxychloride    cements    produced    from,    them   has    been    brought   out. 

"The  relationship  between  active  lime  content  and  physical  properties  of  oxy- 
chloride is  apparent  only  when  average  results  from  many  samples  are  considered. 
Other  factors  may  completely  obscure  the  relation  in  a  test  on  a  single  sample. 

"Active  lime  content  is  accordingly  not  a  definite  indication  of  poor  quality  in 
a  magnesite,  although  a  magnesite  containing  active  lime  in  large  amount  should 
be  regarded  with   suspicion. 

"Physical  tests  of  oxychloride  cements  must  still  be  regarded  as  the  only  safe 
criterion  of  the  quality  of  magnesite  used  in  the  oxychloride  industries."  ' 

The  specifications  and  tests  which  follow,  herewith,  Avere  adopted  as 
'standard'  by  the  National  Association  of  Oxychloride  Mannfactnrers 
at  their  1924  meeting,  and  Avere  furnished  the  author  of  this  bulletin 
through  the  courtesy  of  Mr.  Max  Y.  Seaton,  technical  director  of  the 
Sierra  Magnesite  Company,  who  states  - 

"One  or  two  constants  are  still  lacking  from  the  specifications  but  the  testing 
methods  are  well  developed  and  the  current  publication  represents,  we  believe,  a 
decided  advance  in  oxychloride  cement  testing  practice. 

"It  should  be  mentioned  in  these  as  in  any  other  specifications  in  their  early 
state,  values  are  low  rather  than  high.  For  example,  our  own  plant  here  in  Porter- 
ville  is  consistently  shipping  material  between  20  and  40%  higher  in  strength 
than  the  limits  set  and  with  perhaps  only  one-third  of  the  expansion  changes 
indicated.  Furthermore,  we  are  using  constantly  several  other  tests,  notably  a 
water  resistance  test  which  we  ourselves  believe  is  of  very  great  value  in  judging 
magnesite  quality  which  do  not  appear  in  the  specifications  as  written. 

"Various  members  of  the  Association  are  actively  working  on  improved  methods 
for  determination  of  consistency  of  oxy-chloride  mortars,  for  color  of  oxy-chloride 
cements  rather  than  of  the  magnesite  itself  and  on  improvements  in  the  linear 
change  measurements  which  are  felt  to  be  the  weakest  spot  in  the  specification, 
but  as  yet  there  is  nothing  definite  enough  to  warrant  change  in  the  specifications 
as  they  are  now  written." 

STANDARD   SPECIFICATIONS   AND   TESTS    FOR    PLASTIC    MAGNESIA. 

Adopted  by  the  National  Association   of   Oxychloride  Manufacturers    (1924). 
DEFINITION. 

1.  Plastic  Magnesia  is  a  magnesium  oxide  which,  when  mixed  with  magnesium 
chloride  solution  of  proper  strength  and  with  suitable  fillers,  sets  to  a  hard  cement. 

I.  Chemical  Properties. 
CHEMICAL  LIMITS. 

2.  Although  a  chemical  analysis  may  furnish  information  to  manufacturers  of 
certain  products  in  which  plastic  magnesia  is  used,  no  definite  relations  have  been 
traced  between  the  chemical  composition  of  plastic  magnesia  and  the  physical 
properties  of  the  resulting  oxychloride  cements.  A  chemical  analysis  may  or  may 
not  be  made  at  the  option  of  the  purchaser  but,  provided  the  material  meets  the 
specifications  as  to  physical  properties  herein  contained,  such  chemical  analysis 
shall  not  be  considered  grounds  for  the  rejection  of  the  material. 

II.  Physical    Properties. 
COLOR. 

3.  The  color  of  plastic  magnesia  shall  be  equal  to  or  lighter  than  the  color 
standard  for  the  grade  of  magnesia  specified  by  the  purchaser. 

>  Seaton,    M.    Y.,    Hill,    C.    R.,    and    Stewart,    L.    C,    Action    of   lime    in    magnesium 
oxychloride  cements:  Chem.  &  Met.  Eng.,  Vol.  25,  Aug.   17,  1921. 
2  Personal  communication  to  author,  April  13,  1925. 


MAGNESITE   IN    CAIJFORNIA. 


29 


FINENESS. 

4  The  residue  on  a  standard  No.  100  sieve  shall  not  exceed  three  per  cent  by 
weight.  The  residue  on  a  standard  No.  200  sieve  shall  not  exceed  twenty-five  per 
cent  by  weight. 

TIME  OF  SETTING. 

5  The    plastic    magnesia    when    mixed    in    standard    mix    to    normal    consistency 
(See  Sections  9  and  10)   and  when  stored  under  standard  conditions  (See  Section  11) 
shall    not    develop    initial    set    in   less   than    one   hour.      Final    set   shall    be    attained 
within  eight   hours. 

STRENGTH. 

6  The  average  modulus  of  rupture  in  pounds  per  square  inch  of  not  less  than 
three  standard  test  bars  (or  of  three  tests  on  a  twenty  inch  bar)  (See  Section  44) 
shall  be  equal  to  or  higher  than  the  following: 

Age  of  Test  Storage  Conditions  Modulus  of  Rupture 
Davs  Lbs./Sq.  In. 

1  Standard  500 

7  Standard  900 

7.  The  average  modulus  of  rupture  at  seven  days  shall  be  higher  than  the  value 
at  one  day.  .  ,        ^    ,  ^i.         ^v. 

8  The  average  tensile  strength  in  pounds  per  sq.  in.  of  not  less  than  three 
standard  briquettes  shall  be  equal  to  or  higher  than  the  following : 

Age  of  Tests,  Days  Storage  Conditions  Tensile  Strength 

1  Standard  200 

7  Standard  350 

9.  The  average  tensile  strength  at  seven  days  shall  be  higher  than  the  value 
at  one  day. 

LINEAR  CHANGE. 

10.  Plastic  magnesia  when  mixed  in  standard  mix  to  normal  consistency  shall 
show  not  more  than  the  following  linear  change : 

Storage                                       Initial                                            Final  Linear 

Conditions                             Measurement                             Measurement  Change 

Standard                                 Final  Set                                 24  Hrs.  after  — .10% 

Final   Set 

Standard                                  Final  Set                                 24  Hrs.  after  +.15% 

Final  Set 

III.   Packages,   Marking  and   Storage. 
PACKAGES   AND   MARKING. 

11.  Plastic  magnesia  shall  be  delivered  in  suitable  bags  or  barrels  with  the 
brand  or  name  of  the  manufacturer  plainly  marked  thereon,  unless  shipped  in  bulk. 

STORAGE. 

12.  Plastic  magnesia  shall  be  stored  in  such  manner  as  to  permit  easy  access 
for  proper  inspection  and  identification  of  each  shipment  and  in  a  suitable  weather- 
tight  building  which  will  protect  it  from  dampness. 

IV.   InsDection. 
INSPECTION. 

13.  Every  facility  shall  be  provided  the  purchaser  for  careful  sampling  and 
inspection  either  at  the  mill  or  at  such  other  point  as  may  be  specified  by  the 
terms  of  purchase  agreement  or  contract. 

V.  Rejection. 
REJECTION. 

14.  The  calcined  magnesia  may  be  rejected  if  it  fails  to  meet  any  of  the  require- 
ments of  these  specifications. 

TESTS. 

VI.  Sampling. 
SAMPLING. 

15.  A  composite  sample  shall  be  takt-n  from  each  car  or  fraction  thereof.  Such 
composite  sample  shall  be  prepared  by  mixing  individual  samples  taken  from  at 
least  each  two  thousand  pound  lot  of  the  shipment.  A  composite  sample  shall 
weigh  eight  to  ten  pounds. 

16.  Samjjles  shall  be  shipped  or  stored  in  air-tight  containers.  If  the  sample 
contains  lumps  or  foreign  material,  it  shall  be  passed  through  a  sieve  having  twenty 
mesh  per  linear  inch  to  remove  these. 

17.  Samples  from  individual  packages  in  the  shipment  may  be  separately  tested 
at  the  purchaser's  option.  Failure  of  any  such  individual  sample  to  meet  these 
specifications  may  constitute  cause  for  rejection  of  the  entire  shipment. 


30  CALIFORNIA    STATE    MINING   BUREAU. 

VII.  Determination  of  Color. 
COLOR  STANDARDS. 

18.  .Four  standard  color  samples  shall  bo  used  for  comparison  purposes. 

A.  White. 

B.  Light 

C.  Medium  dark. 

D.  Dark. 

19.  Standard  color  samples  are  in  the  hands  of  the  secretary  of  the  Committee  on 
Magnesite  Specifications  and  will  be  furnished  upon  request. 

METHOD. 

20.  For  comparison  of  color  a  small  amount  of  the  standard  shall  be  placed  In  a 
heap  beside  a  similar  heap  of  the  material  under  tests  on  a  flat  surface.  The  two 
heaps  shall  be  leveled  off  and  brought  to  a  .sharp  junction  by  use  of  a  spatula. 
If  the  material  is  equal  to  or  lighter  than  the  color  sample  with  which  it  is 
compared,  it  shall  be  considered  to  fall  in  the  grade  of  that  sample.  If  darker  in 
color,  it  shall  be  compared  with  the  color  sample  of  the  next  lower  grade. 

Note — Nothing  in  the  specifications  for  color  should  be  taken  to  mean  that  the 
color  grade  of  the  plastic  magnesia  is  an  exact  measure  of  the  color  of  the  cement 
made  therefrom,  although  there  is  some  relation  between  these  colors.  The  color 
of  the  finished  cement  can  only  be  determined  after  making  up  a  trial  lot  from  the 
particular  materials  which  are  to  be  used. 

VIII.   Determination   of   Fineness. 

APPARATUS. 

21.  The  standard  No.  100  and  No.  200  sieves  used  shall  conform  to  the  specifica- 
tions for  standard  sieves  of  the  the  U.  S.  Bureau  of  Standards. 

METHOD. 

2  2.  The  residue  on  No.  200  mesh  sieve  shall  first  be  determined.  A  test  shall  be 
made  with  50  grams  of  plastic  magnesia.  The  sieve  shall  be  thoroughly  clean  and 
dry.  The  magnesia  shall  be  placed  on  the  No.  200  sieve  with  pan  and  cover 
attached,  and  shall  be  held  in  one  hand  in  a  slightly  inclined  position  so  that  the 
sample  will  be  well  distributed  over  the  sieve.  At  the  same  time  gently  striking  the 
side  about  150  times  per  minute  against  the  palm  of  the  other  hand  on  the  upstroke. 
The  sieve  shall  be  turned  every  2  5  strokes  about  one-sixth  of  a  revolution  in  the 
same  direction.  The  operation  shall  continue  until  not  more  than  0.05  gram 
passes  through  in  one  minute  of  continuous  sieving.  The  residue  on  the  sieve  shall 
be  weighed,  and  the  weight  expressed  as  a  per  cent  of  the  weight  of  the  original 
sample.  The  residue  shall  then  be  screened  through  100  mesh  sieve,  using  the 
same  method  of  operation,  and  the  residue  on  100  mesh  sieve  reported. 

2  3.  Mechanical  sieving  devices  may  be  used  but  the  plastic  magnesia  shall  not 
be  rejected  if  it  meets  fineness  requirements  when  tested  by  the  hand  method. 

IX.  Standard   Oxychloride   Cement    Mixture. 
MIX. 

24.  F'or  the  determination  of  setting  time,  modulus  of  rupture,  and  linear  change, 
a  standard  oxychloride   cement  mix  shall   be  prepared  as  follows  : 

(1  part  by  weight  of  plastic  magnesia. 

2  parts  by  weight  of  standard  ground  silica  or  silex. 

5  parts  by  weight  of  standard  silica  sand. 

SILBX. 

25.  The  ground  silica  or  silex  used  shall  be  ground  from  a  pure  silica  sand  or 
from  quartz.  It  shall  consist  essentially  of  pure  silica  (SiOo).  Ninety-five  per  cent 
of  the  material  shall  pass  a  standard  No.  100  sieve  and  75-85  per  cent  of  the  material 
shall  pass  a  standard  No.  200  sieve. 

SAND. 

2  6.  The  sand  to  be  used  shall  be  a  natural  sand  from  Ottawa,  Illinois,  screened 
to  pass  a  No.  20  sieve  and  be  retained  on  a  No.  30  sieve.  This  sand  may  be  obtained 
from  the  Ottawa  Silica  Company,  Ottawa,  Illinois. 

CHLORIDE   SOLUTION. 

2  7.  Magnesium  chloride  solution  shall  be  made  by  dissolving  commercially  pure 
fused,  crystallized  or  flake  magnesium  chloride  in  distilled  water.  The  resulting 
solution  shall  be  adjusted  to  a  gravity  of  22°  Be.  at  60°  F.  The  chloride  used  shall 
contain  a  minimum  of  97  per  cent  MgCl,.  6H,0,  less  than  2  per  cent  CaCl,,  and  less 
than  2  per  cent  MgS04. 

2  8.  Not  over  1500  grams  of  dry  ingredients  Shall  be  used  for  the  purpose  of  an 
individual  mix.  The  three  ingredients  shall  be  thoroughly  mixed  by  hand  in  a 
shallow  iron  or  enameled  ware  pan  until  a  uniform  mix  is  obtained  as  far  as  can 
be  told  by  eye.  An  amount  of  magnesium  chloride  solution,  sufficient  to  bring  the 
mix  to  normal  consistency  shall  be  added,  mixing  being  continued  for  a  minimum 
of  one  minute. 

X.   Normal  Consistency. 

29.  For  determination  of  normal  consistency  a  series  of  consistency  pins  shall 
be  prepared  as  follows : 


MAGNESITE    IN    CALIFORNIA.  31 

APPARATUS. 

30.  Three  pins  are  required,  each  being  a  small  cylinder  of  metal  weighing 
250  grams  and  having  a  flat  cylinder  face.  The  No.  18  pin  shall  have  a  face  18/16 
of  an  inch  in  diameter,  the  No.  16  pin  a  face  of  ]6/16  of  an  inch,  and  the  No.  14 
pin  a  face  14/16  of  an  inch  in  diameter.  If  the  pins  are  made  of  round  bar  steel, 
the  No.  18  pin  will  be  almost  exactly  2  inches  long,  the  No.  16  pin  2i  inches  long, 
and  the  No.  14  pin  3  7/32  inches  long.  Tliese  linear  dimensions  shall  be  taken  as 
only  approximate  and  the  weight  of  the  pin  in  any  case  shall  be  adjusted  to 
250  grams. 

METHOD. 

3.1.  For  determination  of  consistency,  a  pat  of  the  freshly  mixed  mortar  at 
least  one-half  inch  thick  shall  be  leveled  off  witli  a  .spatula  to  a  fairly  true  surface. 
The  consistency  pins  shall  be  gently  lowered  onto  the  surface  and  it  shall  be  noted 
whether  they  are  totally  supported  by  the  plastic  mortar  or  whether  they  sink 
into  the  surface.  The  desired  normal  consistency  is  that  at  which  the  Np.  16 
pin  just  fails  to  make  a  permanent  impression  in  the  plastic  mortar.  Although 
it  is  possible  to  make  determinations  by  means  of  the  No.  16  pin  only,  it  is  far 
easier  to  use  the  No.   14  and  No.   18  pins  for  preliminary  adjustment. 

32.  The  amount  of  chloride  required  for  production  of  normal  consistency  with 
the  standard  mix  given  shall  be  recorded  as  cubic  centimeters  per  gram  of  plastic 
magnesia. 

33.  An  alternative  method  for  determination  of  normal  consistency  is  that  involv- 
ing measurement  of  the  slump  of  a  2x4   cylinder  of  the  plastic   mortar. 

34.  A  steel  or  brass  cylinder  4"  high  and  2"  in  diameter  shall  be  placed  on  a 
level  surface,  filled  with  the  plastic  mortar  and  struck  off  even.  The  cylindrical 
mold  shall  then  be  carefully  raised  in  a  vertical  direction  and  tlie  height  of  the 
resultant  mass  or  mortar  measured.  The  mortar  shall  be  considered  to  have  normal 
consistency  when  the  height  of  the  mass  is:    (This  figure  to  be  developed.) 

35.  If  normal  consistency  is  not  attained  at  the  first  trial,  a  fresh  batch  of  dry 
mix  shall  be  prepared  and  chloride  again  added.  This  process  shall  be  continued 
until  normal  consistency  is  attained  with  a  single  addition  of  chloride. 

XI.  Standard  Storage  Conditions. 
STORAGE  OF  TEST  PIECES. 

36.  All  test  pieces,  whether  used  for  determination  of  setting  time,  strength, 
or  linear  changes,  shall  be  stored  in  air  at  a  temperature  between  60°  and  80°  F. 

XII.   Determination  of  Setting   Time. 

37.  The  time  of  setting  shall  be  determined  by  the  use  of  standard  Gilmore  needles. 
GILMORE  METHOD. 

38.  A  pat  of  standard  mix  having  normal  consistencj'  about  three  inches  in 
diameter  and  one-half  inch  in  thickness  with  a  flat  top,  shall  be  made  and  stored 
under  standard  conditions.  The  magne.sia  shall  be  considered  to  have  its  initial 
set  when  the  pat  will  bear  without  appreciable  indentation  the  Gilmore  needle  one- 
twelfth  inch  in  diameter  loaded  to  weigh  one-fourth  pound.  The  final  set  has  been 
acquired  when  the  pat  will  bear  without  appreciable  indentation  the  Gilmore 
needle  one-twenty-fourth  inch  in  diameter  loaded  to  weigh  one  pound.  In  making 
the  test  the  needle  shall  be  held  in  a  vertical  position  and  applied  lightly  to  the 
surface  of  the  pat. 

AUTOMATIC  MACHINES. 

39.  Any  suitable  automatic  setting  time  machine  may  be  used  in  carrying  out 
the  setting  time  tests,  but  the  plastic  magnesia  shall  not  be  rejected  if  it  meets 
the  setting  time  requirements  of  the  specification  when  tested  by  the  method  described 
above. 

XIII.  Strength    by   Cross   Bending  Tests. 
FORM  OF  TEST  PIECES. 

40.  Modulus  of  rupture  shall  be  determined  by  cross  bending  on  bars  of  the 
standard  mix  one-half  inch  thick,  two  inches  wide,  and  at  least  ten  inches  long. 
•  •  *  Three  tests,  one  at  twenty  inch  and  two  at  ten  inch  spans,  can  be  made 
from   each   bar. 

41.  The  steel  base  plate  and  the  separating  bar  of  the  bar  mold  shall  be  oiled 
slightly  with  a  fairly  heavy  mineral  oil,  any  excess  of  oil  on  the  surface  being 
carefully  avoided.  A  suitable  quantity  of  the  standard  mix  shall  be  prepared, 
brought  to  normal  consistency  and  placed  in  the  molds  by  use  of  an  ordinary 
plasterer's  trowel.  The  plastic  mix  shall  be  brought  to  the  level  of  the  spacing  bars 
with   the  minimum   troweling  possible. 

STORAGE. 

42.  The  bar  frames  shall  be  kept  in  an  atmosphere  of  a  temperature  of  60°  to  80° 
F.  and  a  relative  humidity  of  30  to  70.  Test  bars  shall  remain  in  the  molds  without 
covering  of  any  kind  for  from  eigliteen  to  twent.v-four  hours,  after  which  time 
they  shall  be  removed  and  stored  on  edge  with  at  least  one-half  inch  air  space 
between  bars  in   the  atmosphere  specified  under  standard   storage   conditions. 


32 


CALIFORNIA    STATE    MINING   BUREAU. 


TESTING. 

43.  Modulus  of  rupture  shall  be  determined  by  breaking  such  test  bars  by  apply- 
ing- load  at  the  center  of  a  twenty-inch  or  of  a  ten-inch  span.  Any  simple  cross- 
bending  apparatus  may  be  used.  The  face  of  the  bar  which  was  undermost  i  e 
in  contact  with  the  base  plate  of  the  mold  during  preparation  of  the  bars  '  shall 
have  the  central  knife  edge  of  the  machine  in  contact  with  it.  Load  shall  be  applied 
at  the  approximate  rate  of  fifteen  pounds  per  minute.  The  knife  edges  of  the  cross 
bending  macliine  shall  be  cushioned  by  the  u.se  of  thin  blotting  paper  An  easily 
constructed  cross  bending  machine  is  shown  in  Plate  II  herewith. 

CALCULATION  OF  MODULUS  OF  RUPTURE. 

44.  Modulus    of    rupture    shall    be    calculated    from    the    applied    load    by    use    of 
the  following  formula : 


f= 


3  WI 
2bh= 


Where  f  ==  modulus  of  rupture, 
wrzr  load  applied. 

I  =  length  of  bar  between  centers, 
b  =:  width  of  bar. 
h  =  thickness  of  bar. 


Plate  II. 


-Cross  b  en  ding  Testing  Machine  — 


For  a  one-half  by  two-inch  bar,  broken  by  center  loading  and  supported  on  a 
tweny-inch  center,  f  =  60  W,  or  the  modulus  of  rupture  is  sixty  times  the  applied 
load.      For  ten-inch  span,  f=:30  T\'. 

45.  Careful  workmanship  will  result  in  the  production  of  bars  differing  so  little 
from  the  standard  one-half  inch  thickness  that  the  factor  60  can  be  uniformlj'  used 
for  calculation  of  modulus  of  rupture.  The  thickness  of  bars  varying  from  standard 
dimensions  should  be  determined  to  the  nearest  sixty-fourth  of  an  inch,  and  the 
proper  factor  from  the  table  below  used  for  calculating  modulus  of  rupture. 

Thickness  of  Bar 


35/64 
34/64 
33/64 
32/64 
31/64 
30/64 
29/64 


Factor 
;0"  length 
50.2 
53.2 
56.4 
60.0 
63.9 
68.3 
73.1 


Factor 
10"  length 
25.08 
26.57 
28.21 
30.00 
31.97 
34.13 
36.53 


MACiNKSITI-:    IN    CM. IFOKNIA. 


.in 


3—39802 


34  (lALIPORNIA    STATK    MININii    BUKEAIT. 

46.  Bars  which  are  manifestly  faulty  or  which  give  strengths  differing  more 
than  twenty  per  cent  from  the  average  value  of  all  test  pieces  made  from  the  same 
sample  and  broken  at  the  same  period  shall  not  be  considered  in  determining  modulus 
of  rupture. 

XIV.   Tensile   Strength. 

47.  For  determination  of  tensile  strength,  standard  briquettes  of  the  dimensions 
adopted  for  the  test  nieces  used  in  determination  of  tlie  strengtli  of  Portland  cement 
mortars    (A.  S.  T.  M.  Standards  1921,  p.   546)    shall  be  used. 

TEST  PIECES. 

48.  Immediately  after  mixing,  the  standard  mortar  shall  be  placed  in  the  molds, 
pressing  in  firmly  with  the  thumbs  and  smoothing  off  with  a  trowel  without  ramming. 
Additional  mortar  sliall  be  heaped  above  the  mold  and  smoothed  off  with  the  trowel. 
The  trowel  shall  be  drawn  over  the  mold  in  such  a  manner  as  to  exert  a  moderate 
pressure  on  the  material.  The  mold  shall  then  be  turned  over  and  the  operation  of 
heaping,  thumbing  and  smoothing  off  repeated. 

STORAGE. 

49.  Test  briquettes  shall  remain  in  the  molds  without  covering  of  any  kind  for 
from  eighteen  to  twentj'-four  hours,  after  which  they  shall  be  removed  and  stored 
on  edge  so  that  ample  air  circulation  is  provided  on  all  sides,  in  the  atmosphere 
specified  under  Standard  Storage  Conditions. 

TESTING. 

50.  Tests  shall  be  made  with  any  standard  machine.  The  bearing  surfaces  of  the 
clips  and  briquettes  shall  be  free  from  grains  of  sand  or  dirt.  The  briquettes  shall 
be  carefully  centered  and  the  load  applied  continuously  at  the  rate  of  600  lbs.  per 
minute. 

51.  Briquettes  that  are  manifestly  faulty  or  which  give  strengths  differing  more 
than  fifteen  per  cent,  from  the  average  value  of  all  test  pieces  made  from  the  same 
sample  and  broken  at  the  same  period  shall  not  be  considered  in  determining  the 
tensile  strength. 

XV.    Linear   Change. 

TEST  PIECES. 

5i2.  The  amount  of  movement  of  reference  points  inserted  in  a  bar  of  a  standard 
oxychloride  cement  mix,  two  inches  wide,  one-half  inch  thick,  and  over  ten  inches 
long,  shall  be  determined  and  shall  be  reported  as  linear  change. 

APPARATUS. 

53.  An  instrument  for  determination  of  such  movement  is  the  Berry  Strain  Gauge, 
manufactured  by  H.  C.  Berry  at  the  University  of  Pennsylvania.  This  instru- 
ment is  shown  in  Plate  III  herewith.  Instead  of  the  Berry  Strain  Gauge  any 
suitable  optical  bench  or  similar  method  of  measurement  which  will  give  true  values 
for  the  movement  of  the  reference  points  may  be  employed. 

METHOD. 

54.  Reference  points  can  conveniently  consist  of  small  metal  pieces  of  the  shape 
shown  in  Figure  "C,"  Plate  III.  Each  of  these  pieces  may  have  on  its  surface 
three  indentations  spaced  a  definite  distance  apart.  Such  indentations  can  con- 
veniently be  made  by  the  punch  shown  in  "D,"  Plate  III. 

55.  The  linear  change  test  bar  should  be  prepared  on  a  surface  covered  with 
waxed  paper  so  that  no  possible  attachment  to  the  surface  will  result.  When  the 
bar  is  approaching  initial  set,  the  two  reference  points  shall  be  placed  in  it  by  the 
use  of  the  standard  length  bar  of  the  Berry  Strain  Gauge.  The  spacing  points  on 
this  bar,  which  are  approximately  ten  inches  apart,  should  be  placed  in  the  center 
of  the  three  indentations  in  each  of  the  metal  plates  as  these  plates  are  gradually 
pushed  into  the  still  plastic  material  so  that  these  center  indentations  are  approxi- 
mately ten  inches  apart  when  these  plates  are  placed. 

56."  The  initial  measurement  shall  be  made  at  the  time  when  the  test  bar  reaches 
final  set.  Further  measurement  shall  be  made  at  twenty-four  hour  and  seven  day 
age.  With  a  magnesia  giving  cements  which  show  very  little  linear  change,  only 
the  center  indentations  will  be  needed,  taut  if  linear  change  reaches  a  high  value, 
these  center  indentations  will  fall  outside  of  the  limit  of  the  gauge  and  measurements 
can  then  be  continued  with  the  other  indentations,  proper  addition  or  subtraction 
from  the  gauge  readings  being  made  when  such  change  in  reference  points  is  made. 

PRODUCTION  AND  PRICES. 

In  considering  mineral  ]n'0(lncti(in,  the  tonnage  and  value  of  the 
crude  mineral  is  used  as  far  as  possible.  Magnesite  presents  a  peculiar 
example  of  a  material  which  (except  during  the  war-time  activity  of 
1915-1919)  was  seldom  handled  on  the  market  in  a  crude  state,  it 
being  ordinarily  calcined  and  ground  before  being  sold.  By  taking 
the  average  price  of  unground  calcined  magnesite,  in  sacks,  at  San 


.\rA(i.\ESITK    IN"    rAMFORXIA.  ST) 

Francisco,  less  freight,  and  figuring  from  2  to  2^  tons  of  crude  to  1  of 
calcined,  on  arbitrary  value  for  the  crude  material  at  the  mine  was 
determined  and  used  in  reports  of  the  State  Mining  Bureau,  previous 
to  1915.  On  this  basis  the  assigned  value  per  ton  was  somewhat  hiuher 
than  actual  contract  prices  for  crude  ore,  as  developed  later,  when  it 
began  to  be  sold  in  crude  form. 

Considerable  tonnages  were  shipped  in  a  crude  state  in  1915,  at 
prices  ranging  from  $7  to  $11  per  ton  f.  o.  b.  rail-shipping  point,  or  an 
average  of  about  $9  per  ton. 

In  1916  crude  magnesite  was  contracted  for  at  from  $6  to  $10  per 
ton  f.  0.  b.  rail-shipping  point  or  an  average  of  about  $8  per  ton. 

Prices  for  1917  ranged  higher,  the  value  of  crude  averaging  about 
$9.50  per  ton.  During  the  height  of  the  summer  shipping  season, 
in  July  prices  reached  a  figure  of  $12.50  per  ton,  f.  o.  b.  rail.  BetVn-e 
the  close  of  the  year,  however,  the  market  broke,  due  in  part  to  freight- 
car  embargoes  and  priority  classifications,  and  to  the  competition  of 
the  new  Washington  deposits.  The  1918  magnesite  yield  of  California 
was  reduced  more  than  SO'/f  from  the  1917  figures,  on  account  of  the 
Washington  and  Canadian  competition. 

The  value  of  calcined  magnesite  varies,  the  San  Fraiici.sco  price  for 
1916  ranging  from  $25  to  $-45  per  ton.  which  figure  includes  about 
$4  per  ton  freight.  During  1917  it  ranged  from  $85  to*  $55;  and  in 
1924.  from  $30  ^to  $35. 

The  July,  1918,  quotation  at  New  York  was:  Raw  magnesite 
f.  0.  b.  works,  Pittsburgh,  $30  to  $35  per  ton  :  dead  burned,  per  net 
ton  @  $50  to  $60. 

The  production  of  magnesite  in  California  remained  ({uite  steady 
for  the  5  or  6  years  immediately  antedating  the  outbreak  of  the  war, 
averaging  not  far  from  10,000  tons  of  crude  per  year.  There  was 
practically  no  change  in  conditions  in  1914.  During  that  year  four 
counties,  Alameda.  Santa  Clara,  Sonoma  and  Tulare,  produced  a  total 
of  11,438  tons  of  which  9650  tons  came  from  Tulare  County. 

In  1915  the  output  increased  to  30,721  tons  distributed  among  six 
counties.  Tulare  produced  11,574;  Santa  Clara  7623;  Fresno  and 
Kern    6850,  with  smaller  amounts  from  Sonoma  and  Napa. 


30 


CALIFORNIA    STATE    MINING    BUREAU. 


The  1916  production  of  the  state  wa,s  approximately  5  times  that 
of  1915.    It  totaled  154,052  tons,  distributed  by  counties  as  follows: 


Plate 

IV. 

i 

1 

1 

if" 

i " 

gUo 

50,000 

■ 

1 

\ 
\ 

/ 

/ 

\ 
\ 
\ 

/ 
/ 
/ 

1 

\ 
\ 

\ 

y 

— 

\, 

.' 

~- 

1 



>., 

f 

\ 

\ 
\ 

/ 

/ 
/ 

^> 

- 

-« 

'- 

/» 
• 

\ 

• 

*  "^ 

1 

t 

\, 

- 

'" 

/ 

r 

s 

\ 

/ 

/ 

1 

PRODUCTION  &  AVERAGE  VALUE 
OF 

MAGNESITE- CALIFORNIA 

1887-192+ (iNC) 

CAUrORNlA  STATE  M1NIN6  BUREAU 
Aoompanying   Bulletin  N®79. 

1 

1 

/ 

1 

/ 

\ 

/ 

1 

1 

_ 

■^ 

__, 

— 

^ 

/ 

V 

V 

i 

1887  1890  1895  I9CX3  1905  1910  19IS 

YEARS 

Magnesite  Production,  by  Counties,  1916. 

'County 

Fresno     

Mendocino    

Merced    

Napa 

Santa    Clara   

Sonoma    

Tulare     

Alameda,   Kern,  Placer,  Riverside,   and  Tuolumne* 

Totals    1'54,05 

'  Combined  to  conceal  output  of  a  siiifrle  o])crator  in  each. 


Tons 

Value 

5,829 

$49,082 

300 

2,400 

90 

720 

1-3,960 

108,556 

23,207 

232,156 

11,653 

98,280 

87,606 

737,130 

11,407 

83.560 

$1,311,89: 


MAGNESITE    IX    CAIJFOKNIA.  37 

Tlie  production  l)y  counties  for  the  record  year  1917  is  given  in  the 
following  table,  with  total  crude  values : 

Magnesite   Production,   by  Counties,  1917. 

County  Tons  Value 

Fresno                                                                 6,077  $57,422 

Nana       —               40,329  387,930 

Santa   Claf^'Z^ZZZZ^l^^Z:^^-^""' 9.963  99.287 

Sonoma    5,636  ^A'nll 

Stanislaus                                                       3,196  44.350 

Tulare  A_::::::::::::::::::::::----:: 136,562      1,238,853 

Alameda,     Kern,     Mendocino,    Placer,     Riverside,     San    Benito,  „    „   „ 

Tuolumne  >     1 7.885  87,0o0 

Totals    -- 209,648  $1,976,227 

Californian   Production   in  1924. 

The  i)roduction  of  magnesite  in  California  during  1924  amounted 
to  a  total  of  67,236  tons  of  crude  ore  valued  at  $900,183.  Only  a 
small  part  of  it  was  sold  'crude,'  however,  as  it  is  practically  all  shipped 
in  the  calcined  form.  The  reports  at  hand  show  a  total  of  29,23-5  tons 
shipped  calcined,  of  which  2925  tons  were  dead-burned  and  sold  for 
refractory  purposes,  the  balance  going  to  the  plastic  trade.  The  192-4 
output  is  a  slight  decrease  both  in  quantity  and  value  from  the  1923 
figures  of  73.963  tons  crude  valued  at  .$946,643.  The  average  of  the 
values  reported  for  1924  is  .$13.40  ])er  ton  as  against  $12.80  in  1923.  ^ 

The  more  important  producing  i)roperties  in  1924  were:  iNIaltby  No. 
1  (Western  Magnesite  Development  Co.,  operated  under  lease  by  C.  S. 
Maltby),  on  Red  ]\Iountain,  Santa  Clara  County;  and  the  Sierra 
Magnesite  Company  s  group  near  Porterville,  Tulare  County ;  followed 
in  order,  by  the  Sampson  Peak  mine  (Maltby  No.  3),  San  Benito 
County;  California  ^Magnesia  Company  (old  Harker  mine)  at  Porter- 
ville ;  and  Maltby  No.  2  in  Chiles  Valley,  Napa  County.  Lesser  amounts 
were  reported  mined  in  Fresno  and  Stanislaus  counties. 

Total   Magnesite  Production  of  California. 

Tlie  first  commercial  production  of  magnesite  in  California  was  made 
in  the  latter  part  of  1886  from  the  Cedar  ^^lountain  district,-  southeast 
of  Livermore,  Alameda  County.  Shipments  amounting  to  'several  tons' 
or  'several  carloads'  w^ere  sent  by  rail  to  New  York;  but  there  is  appar- 
ently no  exact  record  of  the  amount  for  that  first  year.  The  statistical 
records  of  the  State  Mining  Bureau  began  with  the  year  1887,  and  the 
table  herewith  shows  the  figures  for  amount  and  value,  annually,  from 
that  time.  Shipments  of  magnesite  from  Napa  County  began  in  1891 
from  the  Snowflake  Mine;  from  the  Red  ^Mountain  deposits  in  Santa 
Clara  County,  in  1899 ;  and  from  Tulare  County  in  1900. 

•  Combined  to  conceal  output  of  a  single  operator  in  each. 
=  See  U.  S.  Geol.  Surv. :  Min.  Res.  of  U.  S.,  1886,  pp.  6,  696. 


38 


CALTFORNI.V    STATE    jriNIXG    BTTREAU. 
Production  of  Magnesite   in   California,  Since  1887. 


Year 

Tons 

Value 

Year 

Tons 

Value 

1887 

1888 

600 
600 
6C0 
600 
1,.500 
1,.500 
1,093 
1,440 
2,200 
1,500 
1,143 
1,263 
1,280 
2,252 
4,726 
2,830 
1,361 
2,850 
3,933 

$9,000 

9,000 

9,000 

9,000 

15.000 

15.000 

10,930 

10,240 

17,000 

11,000 

13,671 

19,075 

18,480 

19,333 

43,0.57 

20,655 

21,515 

9,298 

16,221 

1906 

1907       _-.._- 

4,032 

6,405 
10,5.82 

7,942 
16,.'>70 

8,858 
10,512 

9,632 
11,438 
30,721 
1.54.0.52 
209,048 
83,974 
44,696 
83,695 
47,837 
55,637 
73,963 
67,236 

$40,320 
57.720 

1889 

190S 

80,822 

1890 

1891 

1909 

1910   -  .  

62,588 
113,887 

1892 

1893 

1911 

1912 

1913 

1914..  . 

67,430 
10.5,120 

1894          _. 

77,056 

1895  

114,380 

1896 

1915 

283.461 

1897       -  -  

1916    

1,311,893 

1898 

1917 

1918 

1919 

1,976,227 

1899 

803.492 

1900 

452,094 

1901 

1902 

1903 

1904 __  __ 

1920 

1921 

1922 

1923 

1924 

1,'!33,491 
511,102 
594,665 
946,643 

1905 

900,183 

Totals 

970,701 

89,828,049 

The  chart  (Plate  IV)  shows  graphically  the  total  annual  tonnages 
and  the  average  annual  values  per  ton  of  the  crude  magnesite.  Since 
1906,  the  variations  in  the  price  per  ton  of  magnesite  have  been  pro- 
portionately small.  Though  the  demand  and  resulting  tonnage  output 
increased  many  fold  in  1916  and  3917,  there  was  not  the  same  propor- 
tionate increase  in  the  price  per  ton  as  was  the  case  with  such  minerals 
as  chromite  and  manganese  ores. 

TARIFF  and  IMPORTS. 

Prior  to  1922,  there  was  no  nistoms  duty  on  the  importation  of 
foreign  magnesite  into  the  United  States.  Material  for  refractory  pur- 
poses (mainl}'  dead-burned)  was  received  from  Austria-Hungary;  and 
plastic  magnesite  was  received  mainly  from  Greece.  In  1924,  imports 
from  India  became  a  factor  in  the  plastic  market. 

The  Tariff  Act  of  1922,  which  became  eft'ective  September  22d  of  that 
year,  placed  the  following  import  duties  on  magnesite :  Crude  magnesite 
-iyA  V^^^  l^J- ;  caustic-calcined  magnesite  Hs^  P^'^"  1^-  '■>  dead-burned  and 
grain  magnesite,  not  suitable  for  manufacture  into  oxychloride  cements 
23/40f  per  lb. ;  magnesite  brick,  "{f  per  lb.  and  10%  ad  valorem. 

The  following  tabulation  shows  the  amount  (short  tons)  and  value 
of  magnesite  imported  'for  consumption'  into  the  United  States  for 
the  years  1912-1921: 


Year 

Crude 

Calcined, 

not  purified 

Tons 

Value 

Tons 

Value 

1912 

17,905 

13,240 

13,354 

49,765 

75,345 

30,277 

5,4.32 

6,381 

33,550 

51,993 

73,331 

5,182 

6 

$101,326 

84,911 

.54,677 

2.55,140 

634,447 

232,105 

103,2.33 

103,311 

406,204 

.525,' 52 

976,283 

44,081 

85 

125,252 

167,094 

121,817 

26,. 574 

9,270 

3,966 

19,049 

9,476 

14,780 

6,788 

72,265 

72.955 

64,785 

81,265,339 

1913 

1,672,565 

1914 .. .._ 

;,.323,194 

1915 

232,071 

1916 ..  

204,183 

1917 _.- 

2.32,601 

1918 ...   

824,022 

1919 ._ 

270,721 

1920. 

373,165 

1921 ... .   .. 

250,9.32 

1922  ...... 

1,267,622 

1023 ...   .  ... 

1,022,968 

192^ 

1,172,403 

MAGNESITE    IN    CALIFORNIA.  39 

Duriiii^'  till*  hearings  l)et'oro  tlu'  \Va\s  aiul  Means  Coimiiittee  of  the 
House  and  the  Finance  Counnittee  of  the  KSenate  when  the  matter  of  a 
magnesite  tariff  was  pending  in  1921,  many  valuable  and  interesting 
data  were  brought  out,  as  to  the  relative  (|uantities  and  the  comparative 
value  of  the  American  and  foreign  magnesites  both  refractory  and 
plastic;  also  regarding  costs  of  production.  It  was  shown  that  prior 
to  the  war,  calcined,  refractory  magnesite  was  imported  from  Austria 
at  a  cost  of  $15.75  per  ton,  the  cost  at  the  mines  in  that  country  being 
about  $7  per  ton.  The  railroad  rates  and  dock  charges  amounted  to 
about  $2  per  ton  and  the  ocean  rates  to  Atlantic  ports  were  about  $2 
per  ton.  The  average  cost  of  that  produced  in  the  United  States  was 
shown  to  be  about  $25  per  ton  at  the  mine,  and  the  freight  is  from 
$10  to  $16  per  ton  depending  on  destination.  The  bulk  of  the  con- 
sumption of  refractory  magnesite  in  the  United  States  is  at  the  center 
of  the  steel  industry  (Pittsl)urgh  and  vicinity),  as  only  5.7%  of  the 
npen-hearth  steel  furnaces  of  this  country  are  west  of  the  Mississippi 
River.  West  of  the  Mississippi  there  are  129  copper  converters  which 
would  require  only  2.8%  of  the  dead-burned  magnesite  consumed  in 
the  United  States.  In  1920,  a  total  of  35,000  tons  of  plastic  magnesite 
was  utilized  in  the  United  States. 

"Prior  to  the  war,  the  plastic  business  was  insignificant.  There  was  practically 
no  plastic  business.  Tlie  architects  all  over  the  United  States  were  opposed  to  the 
use  of  magnesite.  The  foreign  magnesite  was  unreliable.  Sometimes  we  had  a 
good  job  and  sometimes  a  bad  one.  With  reference  to  exterior  stucco  in  1914, 
4,000  houses  were  covered  with  it.  Last  year  (1920),  due  to  the  fact  that  we  were 
able  to  oljtain  a  high-grade  magnesite,  we  covered  40,000  houses  with  material  of 
this  kind  made  from  American  magnesite.  *  *  *  "v^e  favor  a  duty  because 
the  Grecian  magnesite  which  is  mostly  used  for  plastic  purpo.ses  is  not  uniform. 
It  is  not  up  to  the  standard."  ' 

In  1924,  in  spite  of  the  tarifl',  importation.s  of  plastic  magnesite  from 
India  reached  a  point  in  tonnage  where  they  seriously  affected  the 
market  for  the  Californiaii  product. 

BIBLIOGRAPHY. 

CAL.  STATE  MIX.  BUR.  Reports  VI,  XII,  XIII,  XIV,  XV,  XVII- 
XX  (inc.)  ;  Bulletins  70,  71,  74,  83,  86,  88,  90,  93,  94,  Mineral  Produc- 
tion for  vears  1914-1923  (mc.)  ;  Buli.  91,  Minerals  of  California,  1923. 

ECKEL,  E.  C— Cements,  Limes  and  Plasters,  1905. 

EXG.  SOC.  WESTERN  PENNSYLVANIA,  Proc.  vol.  29,  pp.  305- 
338.  418-444,  1913. 

JOUR.  A:\IER.  CERAMIC  SOC,  Vol.  3,  No.  3,  pp.  185-246,  Mar. 
1920:  'Magnesite  Refractories,'  bv  J.  S.  .McDowell  and  R.  :\I.  Howp. 

SEATON,  M.  Y.— Proc.  Am.  Soc.  for  Testing  Materials,  Vol.  21, 
1921 ;  Chem.  &  Met.  Eng.,  Vol.  25,  No.  7,  Aug.  17,  1921 ;  Chem.  Age, 
Vol.  31,  pp.  17-22,  Jan.  1923. 

THORPE,  T.  E.— Outlines  of  Industrial  Chemistrv,  li)09. 

U.  S.  GEOL.  SURV.  PUBLICATIONS:  Bulletins  355  and  540:  Min- 
eral Resources  of  the  U.  S.  1913,  1915. 


'  Hearing  before  the  Committee  on  Finance,  U.  S.   Senate,  on  H.  R.   74.56,  Aug.  27, 
1921,  p.   2078. 


40 


CALIFORNIA    STATE    MINING    BUREAU. 


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Photo  No.  6 — Cedar  Mountain  Mag-nesite  Mine.      (The  glory  liole  is  on  Uie  liill 
above  the   large   dump.) 


F- 

> 

te 

-'^.'/t^'--/ 

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Photo  No.  7 — Open  cut   (glory  liolc)    m  Cidai-  .Mountain  Magnesite  Mine. 


MAGNESITE   IX    CAIilFORNIA.  41 


Californian  ^Fixes  and  Plaxts. 

ALAMEDA  COUNTY. 

]\Iao:nesite  was  mined  in  Alameda  County  as  early  as  1886  ^  the 
deposit  being  located  on  Cedar  Mountain  about  13  miles  southeast  of 
Livermore.  The  magnesite  occurs  in  a  decomposed  serpentine  rock 
and  in  a  yellow  clay  in  which  are  imbedded  large  boulders.  It  lies 
in  pockets  and  small  veins,  the  latter  running  in  all  directions. 
Several  of  the  deposits  have  been  exhausted  and  only  one  property 
was  worked  to  any  material  extent.  ]Magnesite  croppings  and  con- 
siderable float  have  been  found  in  Rocky  Ridge,  west  of  Cedar  Moun- 
tain and  separated  from  it  by  the  Arroyo  del  Valle,  but  no  large 
deposits  have  yet  been  uncovered. 

Cedar'  Mountain  Magnesite  Mine  is  in  Sec.  27,  T.  4  S.,  R.  3  E., 
]\r.  1).  y\..  at  an  elevation  of  :>2r)()'  above  sea  level.  It  was  worked 
spasmodically  for  several  years,  and  in  1917  and  1918  Avas  being 
operated  under  a  ten-year  lease  by  J.  W.  Clark  and  D.  ]M.  McDonald 
of  Livermore. 

Over  2000  tons  of  magnesite  were  shipped  from  this  deposit  in 
1916,  and  about  1160  tons  sold  to  the  Hoff  Asbestos  Company,  Oak- 
laiul  in  1917.  This  latter  brought  from  $12  to  $14  per  ton.  Very  little 
work  has  been  done  since  1917;  and  there  is  at  present  (IMay,  1925) 
about  a  carload  of  ore  on  hand  ready  to  ship.  The  magnesite  from 
this  deposit  is,  as  a  rule,  of  excellent  quality. 

There  is  a  series  of  small  magnesite  outcrops  running  east  of  north 
and  dipping  eastward.  Wherever  these  croppings  have  been 
uncovered  or  dug  into  they  show  up  as  tops  of  lenses  of  magnesite 
which  widen  out  below  the  surface.  The  largest  lens  Avas  developed 
by  a  glory  hole  and  cut.  A  tunnel  driven  10  feet  below  the  ])ottom 
connected  with  a  chute,  through  which  the  ore  was  handled.  This  pit 
measures  about  30  feet  across  and  30  feet  deep.  A  drift  driven  from 
the  main  tunnel  southward  50  feet  failed  to  cut  an  orebody.  Work 
has  also  been  done  on  several  croppings  to  the  north  of  the  glory 
hole.  This  property  is  equipped  with  an  oil-burning  flat-hearth-type 
funiace.  built  by  S^nndell  (lessee  in  1914)  designed  especially  to 
jiroduce  'dead-burned'  magnesite,  with  a  capacity  of  5  tons  of  cal- 
cined material  per  24  hours.  Tliis  furnace  has  not  been  used  since 
Swindell  worked  the  mine  in  1914.  It  is  said  to  have  produced 
a  very  uniform  burn,  but  its  cost  of  operation  was  higher  than  that 
of  shaft  furnaces,  as  it  required  more  labor  to  operate,  and  its  fuel 
consumption  was  greater  per  ton  of  magnesite  calcined. 

The  present  lessees  reopened  this  mine  during  the  summer  of  1917 
and  up  to  December,  liad  ship]>ed  several  hundred  tons  of  crude 
magnesite,  mainly  to  the  Iloff  Asbestos  Company  in  Oakland.  Five 
men  were  employed  in  the  development  work.  Water  for  camp  pur- 
poses is  obtained  from  a  well  on  the  i)roperty.  The  area  of  the 
holdings  is  160  acres.  IM.  1.  Crocker.  1023  In.surance  Exchange  Bldg., 
San  Francisco,  owner. 

Bihliof/rapln/:   V.  S.  ({e.il.  Surv..  P.mII.  430.  p.  173.  IIMO. 

'  U.  S.  Geol.  Survey.   Miii.   ]lv!-\  i<(  the   U.  S.,   l.'Si>f.,  pp.   li,  G'JG. 


42 


CALIFORNIA    STATE    MINING    BUREAU. 


Hayes  Ranch  Deposit.  Some  .small  eroppiugs  of  buff-colored 
iiiagnesite  occur  in  the  S\V]  of  Sec.  24,  T.  4  S.,  K.  2  E.,  M.  D.  M., 
about  11  miles  southeast  of  Livermore  near  the  summit  of  Rocky 
Ridge.  Some  large  bouldei-s  of  pure-white  float  are  lying  in  a 
ravine  north  of  and  below  the  outcrop.  Several  tunnels  were  driven 
into  the  hill  under  these  boulders  in  hopes  of  striking  an  orebody 
but  none  was  encountered.  On  the  east  slope  of  the  ridge  numerous 
boulders  have  been  found.     Cuts  have  been  made  along  the  slope 


Photo    No.    8 — Plat-hearth    calcining    furnace    at    Cedar    Mountain 
Magnesite   Mine,    Alameda  County. 

at  several  places  in  all  of  which  boulders  of  high-grade  ore  have 
been  found.  It  is  possible  that  these  boulders  are  in  place,  being 
formed  as  a  gradual  replacement  of  serpentine ;  however,  considerable 
development  would  be  necessary  to  determine  this.  About  25  tons  of 
magnesite  are  lying  on  the  dumps.  There  has  been  no  rock  .shipped 
from  this  prospect  and  it  is  idle.  An  old  wagon  road  from  Livermore 
gives  easy  access  to  the  property. 

Winship  Properties.     K.  D.   Winship,  350  Post  Street,  San  Fran- 
cisco, owner.    J.  W.  Clark  and  D.  McDonald  of  Livermore  as  lessees, 


MAGNESITE   IN    CALIFORNIA. 


43 


in  1917  did  some  prospecting  and  development  work  on  a  series  of 
magnesite  outcrops  on  this  property  in  Sec.  20,  T.  4  S.,  R.  3  E., 
about  one  mile  east  of  tlie  Cedar  Mountain  mine. 

In  the  SAV]  of  Sec.  85,  something  over  a  mile  southwest  from  the 
above,  there  is  a  considerable  body  of  serpentine  Avhieh  extends  west- 
ward at  least  as  far  as  the  center  of  Sec.  34  adjoining.  In  this  area, 
near  the  north-central  part  of  the  SW^  of  Sec.  35,  there  is  a  small  but 
promising  looking  outcrop  of  magnesite.  In  the  serpentine  area  there 
are  also  patches  of  pellets  (see  Photo  No.  9)  and  occasional  veinlets  of 
hydro-magnesite  (a  soft  hydrous  carbonate  of  magnesia).  Some  of  the 
larger  of  these  patches  were  at  one  time  worked  at  the  'magnesia 
mine'  in  Sec.  34.  As  these  sections  lie  in  a  rather  deep  canyon,  a 
branch  of  the  Arroyo  del  Valle,  transportation  out  Avould  be  difficult 
and  expensive. 


^--^.-^i"^- 


Photo    No.    9 — PelUHs   of    hvdro-magnesite    in    serpentine    in    Sec.    34,    T.    4    S., 
R.  3  K.,  M.   D  M.,  Alameda  County. 


44  CALIFORNIA    STATE    MINING    BUREAU. 

FRESNO  COUNTY. 

The  production  of  magiicsite  in  Fresno  County  began  with  a  few 
tons  in  1904,  and  the  total  recorded  yield  to  the  end  of  1913  was 
5643  tons.  The  ontpnt  in  both  1916  and  1917  exceeded  the  total 
production  up  to  and  including  1913.  For  1917  it  amounted  to  6077 
tons,  valued  at  $57,422.  The  properties  so  far  developed  are  all 
located  in  a  small  area  near  Piedra,  the  terminus  of  the  Reedley- 
Piedra  branch  of  the  Santa  Fe  railroad,  about  25  miles  east  of  Fresno. 

John  Anderson.  The  property  of  John  Anderson  of  Piedra  is 
reported  to  contain  deposits  of  magnesite,  but  the  extent  and  import- 
ance of  the  occurrence  has  not  as  yet  been  determined. 

Ferguson  Mine.     (See  Sample  Mine,  also  Sinclair  Bros.  Plant.) 

Piedra  Magnesite  Company  (formerly  Fresno  Magnesite  Mine; 
known  locally  at  one  time  as  Bachler).  This  property  embraces  40 
claims  which' lie  mainly  in  Sec.  5,  T.  13  S.,  R.  24  E.,  I\I.  li.  M.  The  main 
workings  are  on  the  north  side  of  Kings  River  within  one-half  mile  of 
Piedj-a,  the  railroad  shipping  point,  and  expensive  hauling  charges 
are  avoided.  The  Fresno  IMagnesite  mine  Avas  one  of  the  first  to  be 
Avorked  in  Fresno  County,  and  it  has  furnished  the  greater  part  of 
the  output  to  date. 

The  magnesite  occurs  in  a  series  of  veins  in  serpentine.  These  have 
been  operated  by  tunnels.  A  Avinze  sunk  40  feet  beloAV  the  loAA'er 
tunnel  level  is  said  to  have  shoAvn  30  inches  of  magnesite  at  the  top  and 
14  inches  at  the  bottom.    This  shoot  Avas  approximately  114  feet  long. 

The  former  oAvners,  ^I.  F.  Tarpey  et  al.,  of  the  Fresno  Magnesite 
Company,  sold  to  the  Piedra  Magnesite  Company  late  in  1917,  Thos. 
J.  Curran,  Porterville,  manager.  That  company  installed  a  50-ton 
rotary  kiln  alongside  the  railroad  at  Piedra,  AA^hich  displaced  the  old 
stack  furnace  of  25  tons  daily  capacity  at  the  mine.  The  property 
has  been  idle  since  1918. 

Bibliography:  Cal.  State  Min.  Bur.,  Report  on  Mines  &  Mineral 
Resources  of  Fresno  Co.,  July,  1915 ;  also  Report  XTV.  U.  S. 
Ceol.  Surv.,  Min.  Res.  1917.  p.  67. 

Piedra  Mine  (also  knoAA^n  as  Ward).  The  Piedra  Mine  is  located  in 
Sec.  9,  T.  13  S.,  R.  24  E.,  M.  D.  M.  It  lies  south  of  the  Fresno  Magne- 
site mine  and  has  equal,  if  not  better,  shipping  facilities,  being  on  the 
south  side  of  Kings  River  aboA^e  the  railroad  tracks.  A  short  gravity 
tramAA'ay  Avould  land  the  material  at  the  railroad. 

The  property  lies  on  the  rounded  north  face  of  a  hill  Avhich  sup- 
ports the  groAA'th  of  a  fcAv  scattered  oak  trees. 

The  magnesite  occurs  as  veins  in  peridotite  and  is  of  No.  1  grade, 
carrying  98%  MgCOo,  1.2%  SiO.  and  0.6-0.8%-  CaO.  A  cro.sscut  adit 
155  feet  in  length  cuts  a  4-foot  vein  striking  N.  65°  E.  and  dipping 
80°  N.  The  tunnel  has  exposed  the  vein  20  feet  beloAv  the  surface 
outcrop,  Avhich  is  over  225  feet  in  length.  Another  adit  crosscuts  a 
parallel  vein  at  40  feet  and  folloAvs  it  for  80  feet.  This  vein  averages 
30  inches  in  Avidth,  strikes  N.  50°  E.,  and  dips  85°  N.  The  8-foot  vein 
described  in  earlier  reports^  narroAved  to  about  4  feet  at  a  depth  of 
14  feet. 


'  Bradlev.    AV.    AV.,    Mines    and    Mineral    Resources    of    Fresno    County :    Cal.    State 
Min.   Bur..  Report  XIA',  p.  455,  1915. 


MAGNESITE    IN    CAl.IPORNIA. 


45 


Jj.  F.  Ward,  Oakland,  California,  owns  the  mine,  which  has  been 
operated  by  various  leasers.  In  part,  the  ore  has  been  shipped  crude; 
and  in  part,  calcined  in  the  furnace  of  Sinclair  Bros,  at  Piedra,  just 
below  the  Ward  mine.  The  latest  operations  were  in  the  summer  of 
1924,  when  a  small  tonnao;e  was  taken  out  ])y  Wm.  Clear}^  lessee,  and 
calcined  at  Piedra. 

Dr.  Powers  had  a  lease  in  1917  on  the  magnesite  property  of  Mrs. 
Snyder,  located  east  of  the  Fresno  ^lagnesite  mine,  near  Piedra.    Two 


Photo    No.     10 — Magnesite     calcining    furnace     of     Sinclair     Bros. 
(Ferguson),    at    Piedra,    Fresno    County.  Capacity,    25    tons    of- 
crude  ore  per  day. 

men  were  then  working  on  a  small  vein,  but  nothing  has  been  done 
since. 

Sample  Mine.  This  mine  owned  by  W.  C.  Sample,  is  on  Holland 
Creek  south  of  Academy,  and  is  leased  to  A.  ]).  Ferguson,  2975 
McKonzie  Ave.,  Fresno.  Ore  from  tliis  mine  was  hauled  (1922  and 
192."?)  to  the  calcining  plant  of  Sinclair  liros.  (bought  by  E.  E.  Fergu- 
son, son  of  A.  D.  Ferguson),  at  I'iedra,  11  miles  by  truck.  Ferguson 
reports  having  shijjped  many  carloads  analyzing  as  low  as  0.4%  CaO. 
Silica  was  as  high  as  2()'.i,  l)ut  not  ol)jectionable  as  the  product  was 
used  for  plastic  purposes,     idle  in  1924. 


4(5  CATJPORNIA    STATE    MINING    lUTREATT. 

J.  B.  Siebert,  address  Sanger,  star  route,  has  four  claims  above  the 
Fresno  Magnesite  mine  from  whieh  one  car  of  ore  was  shipped  in 
1916.  The  material  had  to  be  sorted  at  Porterville  and  he  r<'eeived 
only  .$100  for  the  lot. 

■Sinclair  Bros.  Plant.  This  i)lant  (M))itaining  a  stack  kihi  witli 
capacity  for  handling  25  tons  of  crude  magnesite  i)er  day  Avas  l)uilt 
by  Sinclair  Bros,  in  1918.  It  was  sold  to  E.  C.  Ferguson  in  1922. 
This  furnace  has  been  utilized  for  calcining  ore  mainly  from  the 
Ward  mine  near  by  and  the  Sample  mine  south  of  Academy.  Sinclair 
informed  the  writer  (in  1920)  that  by  careful  temperature  regulation, 
using  an  electric  pyrometer,  they  obtained  caustic  magnesite  at 
800°-900°  with  not  to  exceed  4%  CO.  remaining,  yielding  "a  more 
active  MgO." 

R.  S.  Snyder  has  a  showing  of  magnesite  on  property  adjoining  and 
east  of  the  Fresno  Magnesite  mine. 

Wm.  Terrill,  in  1917,  had  a  lease  on  a  magnesite  property  located 
3^  miles  northwest  of  Piedra. 

Vance  property.  The  Vance  holdings  consist  of  four  claims  situated 
about  six  miles  north  of  Piedra.  Some  development  work  was  done 
in  1917. 


MAGNESITE    IN    CiAT.IFORNIA. 


47 


KERN  COUNTY. 

A  new  type  of  deposit  of!  magnesite  was  developed  in  Kern  County 
in  1911,  and  shortly  afterward  was  first  described  by  Gale  ^  in  part 
as  follows: 

"The  deposit  is  situated  about  one-li:iIf  to  three-quartei  s  of  a  mile  northeast 
of  Bissell  Station.  The  only  developments  tliat  had  been  made  up  to  March  8, 
1'j12,  consisted  of  a  series  of  pits  and  a  few  shallow  shafts  opening  the  deposit 
tlirough  a  stretch  of  about  a  quarter  of  a  mile. 

"This  deposit  is  unique  in  being  the  only  occurrence  of  magnesite  of  evident 
sedimentary  origin  that  lias  been  reported  in  tliis  country.  Some  deposits  in 
Quebec  are  described  as  probably  of  sedimentary  origin,  but  liitherto  all  tlie  Cali- 
fornia magnesite  lias  been  described  as  associated  with  and  evidently  derived  from 
altered  basic  intrusive  igneous  rocks  carrying  a  large  percentage  of  magnesia. 

"The  magnesite  at  Bissell  occurs  in  definitely  bedded  form,  interstratifled  witli 
clays  and  clay  shales,  and  evidently  forming  a  part  of  the  same  series  tliat  shows 
massive  ledges  of  limestone  and  chert.v  layers  in  outcrop  near  by.  The  clay  beds 
are  prevailingly  dull  greenish  ))ut  in  places  consist  of  a  very  dai'k  carbonaceous 
material.  In  the  low  rounded  hills  that  characterize  this  part  of  tlie  Mojave  Desert 
the  strata  in  general  do  not  outcrop  conspicuously  and  consequently  are  not  readily 
traced.  The  limestone  and  cherty  ledges  are  visible,  however,  and  recent  prospect- 
ing has  revealed  the  softer  magnesite-bearing  beds  to  some  extent.  The  outcrops 
piospected  occur  on  the  south  slope  of  a  low  ridge. 


Photo  No.   11 — General  view  of  Bissell  Magnesite  Mine,   looking  eastward. 


"The  magnesite  can  be  obtained  in  very  clean  white  masses,  as  it  readily  separates 
from  the  inclosing  clay.  It  is  pure  white,  very  fine  grained,  and  compact,  breaking 
with  a  china-like  conchoidal  fracture,  such  as  is  characteristic  of  most  magnesite. 
On  e.x-posure  to  the  air,  however,  the  material  from  tliis  deposit  shows  a  tendency 
to  break  down  that  has  not  been  noted  at  other  deposits.  A  rain  a  short  time 
before  the  date  of  visit  had  wet  the  magnesite  on  the  prospect  dumps  and  the 
lumps  were  said  to  ha\'e  cracked  and  broken  down  like  lime  starting  to  slack.  It 
was  observed  that  only  the  more  freshly  dug  material  afforded  solid  specimens. 
Disintegration  by  weathering  may  give  to  the  surface  of  these  deposits  a  some- 
what coar.ser  and  more  earthy  textmc  than  tlic  porcelain-like  fracture  characteristic 
of  magnesite,  but  the  inck  has  nevertlieless  a  marked  similarity  to  the  typical 
magnesite.  It  would  perhaps  l)e  surprising  if  a  sedimentary  deposit  of  this  sort 
should  be  found  to  cairy  as  low  a  iiercentage  of  lime  as  is  contained  in  many  of  the 
other  California  magnesite.^. 

"All  other  California  niagnesitf  (If)iosits,  so  far  as  known,  occur  as  veins  in 
conniction  with  serpentinized  magnesia n  rocks,  iisuall.v  refeiTcd  to  as  serpentines. 
No  exidence  of  any  assrxiation  with  Sfi-piMit hies  was  observed  at  the  Bissell  deposits. 

".V  sugestion  as  to  the  possible  origin  of  the.se  deposits  may  be  found  in  con- 
sidciing  the  charactei-  of  the  salines  conmionly  associated  with  the  lake-bed  deposits 
of  the  desert  basins.  Magnesium  is  commonl>-  ab.sent  from  the  soluble  salts  of  the 
desert-lake    salines,    although    magnesimu    .salts    are    common    constituents    of    spring 


Bull. 


'Gale,   H.    S.,   Magnesite   deposits   in    California   and   Nevada:    U.    S    Geol     Survev 
11.   540,   pp.   512-516,   1914.  "    '='"'*'^^' 


48 


(!ALIFf)RNIA    STATE    MININ<!    BUREAU. 


waters  in  Tertiary  and  Mesozoiu  rocks  in  other  parts  of  the  western  states.  Many 
of  the  lake  waters  now  in  the  Great  Basin  area  are  rich  in  sodium  carbonate, 
whicli  would  of  course  precipitate  as  magnesium  carbonate  any  soluble  magnesium 
salt  introduced.  Possibly,  therefore,  spring  or  other  waters  bearing  magnesium 
salts,  generally  the  sulphate,  entered  a  lake  basin  containing  sodium  carbonate  in 
solution,  with  the  result  that  magnesium  carbonate  was  precipitated,  forming 
bedded  deposits.  The  relatively  greater  solubility  of  magnesium  sulphate  compared 
with   calcium   sulphate,    would   perhaps   explain    the   predominance    of   magnesia   over 


Photo    No.    12 — Bissell    Magnesite    Mine.     Showing    stratification,    also    folding    and 
faulting.      Photo   by   C.   A.   Waring. 

Plate  V. 


SKETCH     SECTION 


ISSELL    QUARRY 

KERN     CO.    CAL. 


ay     C.A.W/»RIN<J 


^- 

LEGEND 

1 

"3 

^ 

^^'>' 

' 

^           ' ^      ^     ^^^ 

V      '^       -       \            /.      ^V        . 

'.^^t^^^\ 

^ 
^ 
^ 

V       -        "     V       '      < 

CLAY 

magnesite: 

/OO  -  ft 

LEVEL 

Ca/ifornia    Sfaf'e  M/n/^ig  Bureau. 


Accompanying  Bu//et/n    /V-  ^S 


lime  in  the  resulting  precipitate.  It  is  alsn  suggested  that  if  this  magnesite  were 
thus  precipitated,  it  would  probably  Ijo  in  part  at  least,  laid  down  as  hydro- 
magnesite,  and  that  it  would  have  been  deposited  more  thickly  near  the  source 
of  supply  and  thus  the  beds  would  necessarily  be  lenticular." 

The  Bissell  deposit  lias  l)eon  extensively  developed  since  the  report 
to  which  we  arc  indebted  for  the  above  extracts  was  published.    There 


MAGNESITE    IN    CALIFORNIA. 


49 


is  an  open  cut  2200  feet  in  leiiiith  Avitli  a  iiiaxiiinun  depth  of  30'  and 
two  shafts,  No.  1  and  No.  2. 

One  shaft  has  reached  a  de])th  of  100  feet  and  from  the  bottom  a 
drift  Avas  run  west  400  feet,  and  another  east  200  feet,  and  a  series 
of  raises  put  up  cutting  the  different  sti'ata.  The  ma.miesite  occurs  in 
beds  with  clay,  clay  shales  and  limestone,  striking  from  N.  60°  AV.  to 
N.  85°  W.,  and  dipping  from  25°  to  45°  S.  Some  of  the  shale  strata 
are  somewhat  sandy.  The  magnesite  strata  vary  in  thickness  from 
mere  seams  up  to  beds  4  feet  in  thickness,  the  major  portion  running 
from  8  to  18  inches.  On  the  west  end  the  orebody  is  cut  off  by  a 
fault  running  NE.  The  accompanying  clays  and  limestone  are  magne- 
sium bearing.     There  is  considerable  fraginental  chalcedony  in  the 


Photo  No.   13 — Bissell  Magnesite  deposit,  sliowing  stratificati<jn,  and  dip  soutli. 

f  surface  material  overlying  the  magnesite  strata.     An  analysis  of  the 
magnesite  produced  shows : 

SiOz 7% 

CaCO, 2% 

Fe  and  Al ^ _      3% 

MgCO.T    83-85% 

MgO    35-40% 

In  October,  1924.  the  mine  was  visited  by  the  writer,  and  specimens 
collected  of  the  magnesite  which  had  lain  exposed  to  the  Aveather  for 
sevei-al  seasons.  Some  were  friable  and  some  solid.  These  wei'e  exam- 
ined <|ualitatively  in  the  laboratory  of  the  State  IMining  liureau.  The 
chief  impui-ity  was  silica,  varying  appariMitly  from  5'/{  to  10'  i ,  being 
higher  in  the  'solid'  specimens.  Lime  was  relatively  low,  a])parently 
not  over  1%. 

The  property  lies  at  an  elevation  of  2500'  above  sea-level.  In  1917- 
1918,  it  was  being  worked  with  a  drag-line  scraper  attached  to  a  12 
h.  p.  gasoline  hoist  by  means  of  which  the  overhui'den  was  removed. 
Twenty  men  were   employed   and   from   300  to  500  tons  i)er  month 

4—398(12 


50  CALIFORNIA    STATE    MINING    BUREAU. 

shipped  to  the  Internatioiial  Kefractories  Company's  kilns  at  San 
Diego,  where  it  was  calcined  with  magnesite  from  Santa  Margarita 
Island. 

The  Southern  Pacific  Company  is  the  owner  of  the  property  which 
consists  of  Sec.  11,  T.  10  N.,  R.  il  W.,  S.  B.  M.  It  was  earlier  leased 
to  the  R«"x  Plaster  Company  of  Los  Angeles,  and  subleased  by  them 
to  P.  A.  Wickham,  Los  Angeles.  Dr.  R.  Schiffman  of  Los  Angeles, 
president  of  the  International  ^Magnesite  Company  was  the  lessee  i)i 
1917-1918.    Idle  1923-1924. 

Bibliography:  Cal.  State  Min.  Bur.,  Report  XIV,  p.  519.  U.  S. 
Geol.  Survev,  Bull.  540.  pp.  512-516.  Eng.  &  Min.  Jour.  Dec. 
2,  1916. 

Walker's  Pass.  Magnesite  is  said  to  exist  in  Walker's  Pass  in  the 
Sierra  IMadre  ^Mountains,  east  of  Bakersfield.  It  appears  to  be  too  far 
from  railroad  transportation  to  be  of  economic  importance.  A  speci- 
men of  the  magnesite  seen  in  Bakersfield  was  solid  and  of  good  white 
color. 

Bibliogrnphy.  U.  S.  Geol.  Survey  Bull.  355. 


MAGNESITE    IN    CALIFORNIA. 


51 


KINGS  COUNTY. 

Kings  Magnesite  Company,  .1.  W.  and  »).  A.  Adclshacli,  ami  V.  L. 
Smith,  copartnei-s,  I'arkficld,  California.  This  conipaiiy,  in  IDlfi, 
located  4  claims  in  Sec.  20,  T.  2.S  S..  R.  K)  E..  M.  D.  M.,  Kings  (Jonnty. 
and  .">  claims  in  Sec.  26,  T.  2)^  S.,  K  15  E.,  Monterey  Connty,  east 
of  Tarklield.  When  visited  by  the  writer  in  September,  1{)17,  work 
in  several  open  cnts  to  a  maxinuim  depth  of  'M)'  had  developed  a 
series  of  'bonlders'  or  segregations  in  serpentine.  Shipments  totaling 
100  tons  of  calcined  material  were  made  during  the  summer  of  1917 ; 
and  there  was  approximately  300— 1€0  tons  of  crude  ore,  in  sight,  when 
they  shut  down  for  the  winter. 

Calcining  was  done  in  the  10-ton  Scott,  fine-ore.  quicksilver  furnace 
of  the  Kings  Quicksilver  mine  described  by  Bradley^  (see  Photo 
No.   14),  using  oil  for  fuel.     The   operators  stated  that,  while   this 


I'noTi)  No.  14 — Scott,  fine-ore  quicksilver  furnace  at  Kings  Mine,  Kings  County, 
used  for  calcining  magnesite. 

furnace  would  hold  14  tons  of  magnesite,  their  avc^rage  was  8  tons 
burned  per  day.  The  ore  was  crushed  to  pass  a  1-inch  grizzly  before 
charging  to  the  furnace.  Calcining  of  fine  ore  proved  successful  in 
this  furnace.  (See  also  Western  Magnesite  Development  Company, 
in  Santa  Clara  County,  post).  Consumption  of  oil  amounted  to  2h  bbl. 
per  24  hours,  and  cost  (1917),  $1.45  i)er  bbl.  at  Cholame,  and  $2.75-$3 
at  the  furnace.  The  cost  of  hauling  the  crude  ore  from  mine  to 
furnace  was  $1  per  ton.  The  calcined  product  was  hauled  by  motor 
truck  to  the  railroad  at  San  ^liguel  (about  40  miles).  There  have 
apparcntlv  been  no  shipments  of  maenesite  from  this  pi-opcrlx'  since 
1917. 


'  Bradlev,   W.    W..    Quicl<silv(r   resources   of   Califcrnia  :    Cal.    State   Min.    Uur.    Bull. 
rs.  p.   51,   1!)1S. 


52  CALIFORNIA    STATE    MINING    BUREAU. 

LOS  ANGELES  COUNTY. 

At  one  point  on  Prince  No.  1  graphite  claim  of  the  California 
Graphite  Company,  18  miles  from  Saiigus,  an  outcrop  of  inagnesite 
about  8  feet  wide  was  observed  by  the  writer^  during  an  examina- 
tion of  the  graphite  deposits  in  May,  1916.  The  inagnesite  appeared 
to  be  in  a  local  area  of  serpentine,  but  no  work  had  been  done  on  it. 
California  Graphite  Company,  owner,  G.  A.  Skinner,  president,  Box 
157,  Saugus. 

MENDOCINO  COUNTY.- 

The  known  occurrences  of  magnesite  in  Mendocino  County  are  few 
and  small,  and  commercial  production  started  in  1916,  when  about 
300  tons  were  shipped.  A  similar,  small  output  was  also  made  in 
1917.  Several  of  the  larger  deposits  have  apparently  been  exhausted. 
Unless  others,  not  at  the  present  writing  known,  are  found,  there  will 
be  no  dependable  production  from  this  county. 

Hixon  Ranch  (formerly  Vassar  Ranch).  J.  S.  Woods  of  Preston, 
in  1917,  was  mining  magnesite  in  Sec.  11,  T.  12  N.,  R.  11  W.,  M.  D.  M., 
six  miles  by  road  north  of  Preston.  The  station  is  about  half  this 
distance  in  an  air  line,  but  the  Russian  River  has  to  be  crossed  to 
reach  it  and  there  is  no  bridge  near  the  ranch.  There  are  a  number 
of  croppings  of  magnesite  along  the  slope  of  the  ridge  about  1000 
feet  east  of  the  river.  The  croppings  are  small  and  irregular,  aud 
the  orebodies  are  not  continvious  with  depth.  They  lie  in  the  decom- 
posed serpentine  covering  the  ridge.  The  deposit  that  was  being  mined 
is  about  250  feet  above  the  river.  It  has  been  worked  to  a  depth  of 
eight  feet,  and  there  were,  when  visited,  approximately  fifty  tons 
of  white  magnesite  ready  to  be  shipped,  on  the  stock  pile.  The 
other  deposits  higher  up  the  ridge,  described  by  Hess "  have  been 
worked  out,  some  by  A¥oods  in  1917,  and  others  by  Arthur  McCray  of 
Cloverdale. 

Bihlioijraplnr.  Cal.   State  Min.   Bur.,  Report  XIV,  p.  422;   Bull. 
38,  p.  328.    U.  S.  Geol.  Survey,  Bull.  355,  p.  21. 

Southard  Ranch  Deposit.  A  ledge  of  magnesite  four  feet  wide 
and  fifty  feet  long  was  taken  out  by  an  open  cut.  The  vein  was 
vertical  between  walls  of  hard  serpentine.  At  a  depth  of  thirty  feet 
it  pinched  down  to  10".  As  it  was  then  too  small  to  mine  further 
at  a  profit,  work  ceased.  It  was  developed  during  1916  by  J.  C. 
Duffield  and  Chas.  Whited  of  Willits,  who  shipped  out  150  tons  of 
high-grade  magnesite.  The  ore  had  to  be  hauled  two  miles  to  the 
railroad  at  Willits.  There  are  no  other  exposures  known  in  the 
vicinity. 

MERCED  COUNTY. 

The  production  of  magnesite  reported  in  1916  from  Merced  County 
(see  p.  36,  ante)  was  probably  from  the  Quinto  Creek  deposits  just 
over  the  line  in  Stanislaus  County. 

1  Cal.  State  Min.  Bur.,  Report  on  mines  and  mineral  resources  of  Los  Angeles  et  al., 
counties,  p.  44,   1917;  also  in  Report  XV,  p.   504. 

-  Some  of  the  data  embodied  in  the  report  on  Mendocino,  Napa,  Santa  Clara 
and  Sonoma  counties,  was  furnished  Vjy  Ralph  W.  Stone  of  the  U.  S.  Geological 
Survey,  who  in  September,   1917,  visited  several  of  the  properties. 

'  Hess,  F.  L.,  The  magnesite  deposits  of  California  :  U.  S.  Geol.  Surv.,  Bull.  355, 
p.  21.   1908. 


MAGNESITE    IN    CALIFORNIA.  53 

MONTEREY  COUNTY. 

L.  E.  Bedell  of  Parkfield,  in  1914,  made  iDcatioiis  on  a  deposit  of 
niagnesite  in  See.  28,  T.  23  S..  R.  15  E.,  M.  D.  M.,  east  of  Parkfield. 
It  is  as  yet  undeveloped,  except  for  a  small  amount  of  trenching 
(lone  in  1916-1917. 

Bibliography:  Report  XV,  p.  607. 

King's  Magnesite  Company,  J.  W.  and  J.  A.  Adelsbaeh,  and  V.  L. 
^^iiiith,  copartners.  Parkfield.  Cal.  This  partnership,  in  addition  to 
claims  in  Kintrs  County  to  the  east,  located  3  claims  in  Sec.  26,  T.  23 
S..  R.  15  E..  M.  D.  M.,"  Monterey  County,  in  1916.    Undeveloped. 


NAPA  COUNTY. 

]Magiiesite  was  first  produced  on  a  commercial  basis  from  Napa 
County  in  1891.  it  being  the  second  county  in  the  state  to  start  this 
important  industry.  For  ten  years  followinsi',  large  tonnages  of  the 
rock,  mostly  in  the  crude  state,  were  shipped  out,  then  production 
dropped  off  abruptly  and  very  little  ore  was  mined  up  to  1915. 
The  demands  imposed  by  the  war  caused  several  of  the  old  properties 
to  ])e  reopened,  and  the  county  became  an  important  producer. 

All  of  the  known  deposits  in  this  county  are  situated  east  of  Napa 
\^alley  in  Chiles  and  Pope  valleys,  separated  from  the  larger  valley 
by  rough  hills,  Avith  long  and  difficult  hauls  to  the  railroad  at  Ruther- 
ford, the  nearest  shipping  station.  Prospects  for  constructing  a 
railroad  to  traverse  these  valleys  on  its  way  to  Lake  County,  from 
the  Napa  Valley,  have  been  agitated  for  many  years,  and  should 
these  plans  be  carried  out,  it  would  still  further  stimulate  this 
industry.  ]\Iagnesite  could  then  be  shipped  throughout  the  year. 
As  it  is.  the  roads  are  now  impassable  for  motor  trucks  during  the 
rainy  season. 

Bibliographij:  Cal.  State  Min.  Bur.,  Report  XIV,  p.  274;  Bull. 
38,  p.  328.     U.  S.  Geol.  Survey,  Bull.  355,  p.  28. 

Berthenia  Mine,  in  Soda  Canon,  12  miles  east  of  Rutherford,  S.  H. 
Delmater,  Chiles,  owner;  adjoins  Matthai  group.     Idle. 

Bibliography:  Reports  XII,  p.  328;  XIII,  p.  505;  XIV,  p.  274. 
Blanco  Mine  (see  Tulare  ^Mining  Co.;  also  ]Maltby  No.  2). 

Elder  or  Detert  Mine,  (formerly  known  as  the  Matthai  Mine,  also 
Cleveland),  is  located  in  Sec.  36^  T.  8  X.,  R.  4  W..  :\I.  D.  .AI.,  the 
'North  ]\line'  being  in  Soda  Creek  Caiion  just  above  the  road,  and 
the  'South  ]\Iine'  one-quarter  mile  to  the  southeast  and  on  the  north 
bank  of  Greasy  Camp  Creek.  At  the  'North  ^line'  irregular  veins 
and  masses  of  magnesite  were  mined  by  open  cuts  years  ago.  A 
300'  tunnel  driven  north  60'  below  it,  cut  a  vein  at  120'  from  entry, 
having  a  course  AV.,  and  dip  of  25°  S.  It  varies  from  15'  to  24' 
thick  and  lias  been  partly  stoped.  Several  hundred  tons  of  ore  are 
exposed.  Beyond  this  vein  are  only  a  stringer  and  l)ouhlers  of 
magnesite  in  soft  dark  serpentine. 

A  good  road  leads  from  the  camp  on  Soda  Creek  around  the  hill 
to  the  South  Mine.    Production  here  has  been  from  a  quarry  on  a 


54 


CALIFORNIA    STATE    MINING   BUREAU. 


blanket  vein  2'  to  1(K  thick,  faulted  or  slipped,  and  carrying  large 
horses  of  serpentine.  Short  tunnels  or  galleries  driven  in  the  face  of 
the  quarry  disclose  serpentine  behind  the  present  working  face. 
There  were  approximately  sixty  tons  of  hard,  white  niagnesite  on  the 
dump,  when  visited.  Ten  men  were  employed  and  the  production 
was  about  thirty  tons  daily  in  1917-1918.  The  niagnesite  is  hauled 
without  calcining  sixteen  miles  to  Rutherford  from  which  point  it 
is  shipped.  W.  F.  Detert  of  San  Francisco  has  a  lease  on  the  prop- 
ertv  which  was  operated  by  Geo.  W.  Elder  of  San  Francisco.  Idle 
1924. 

Maltby  No.  2  Mine,  C.  S.  Maltby,  Humboldt  Bank  Bldg.,  San  Fran 
Cisco,  lessee.     The  lease  covers  the  old  Blanco  and  the  Snowflake 
mines,  owned  by  the  Tulare  Mining  Company,  the  first-named  hav- 
ing been  operated  by  that   company  during  1917   and  1918.     They 


Photo   No.    15 — Calcining   plant   at   Maltby   No.    2    Mine,    Chiles  Valley,    Napa 
County.     Producing-  dead-burned  magnesite  in  a  rotary  kiln. 

were  among  the  first  magnesite  mines  to  be  Avorked  in  California, 
shi])ments  having  begun  in  1891  and  continuing  for  ten  years  at  a 
rate  of  over  1000  tons  per  year.  They  are  in  Sec.  28,  T.  8  N..  R.  4  W., 
M.  D.  M.,  about  two  miles  south  of  the  old  Chiles  mill  in  Chiles 
Valley. 

After  taking  over  the  property  in  February,  1928,  the  present 
lessee  drove  a  new  adit  in  the  Blanco  ground  1000'  long  which 
crosscuts  the  vein  at  78'  on  the  dip  (or  5-3'  vertical)  lower  than  the 
bottom  level  of  the  former  operators.  Drifts  were  run  100'  north  and 
165'  south,  the  vein  showing  an  average  of  H'  in  width.  On  the  ui)per 
level,  at  the  south  end,  the  vein  is  seen  to  be  split  into  two  parts. 
The   ore  is  broken   down  by  overhand  stojiing,   and  the  small  pro- 


MAGNESITE   IN    CALIFORNIA.  55 

portion  of  waste  is  sorted  in  the  stopes,  by  forks  and  by  hand,  and 
piled  back  for  tilling. 

Calcining:  equipment  consists  (see  Photo  No.  15)  of  a  rotary  kiln, 
■iV  inside  diameter,  by  50'  long,  driven  by  a  6  h.  p.  gas  engine  at 
one  revolution  per  1  min.  and  58  sec,  and  oil  fired.  The  ore  is 
crushed  to  pass  1-inch  mesh  before  charging  to  the  furnace,  and 
is  dead-burned  for  refractory  pur])oses,  analyses  showing  an  average 
of  6%  Fe^O,.;.  The  output  of  the  furnace  is  15  tons  of  calcined 
material  per  24  hours.  This  rotary  kiln  was  formerly  in  use  for 
(|uieksilver  reduction  at  the  Bella  Union  quicksilver  mine  near  Oak- 
ville  in  the  same  county.  The  calcines  as  discharged  from  the 
furnace  are  raised  by  a  bucket  elevator  and  run  over  a  sheet-iron 
chute  to  the  bunker,  from  which  the  motor  trucks  are  loaded  which 
haul  the  product  to  the  railroad  at  Rutherford,  at  a  cost  of  $2.25 
per  ton.  ]\Ialtby  states  that  he  has  had  a  ready  sale,  mainly  on  the 
Pacific  Coast,  for  the  dead-burned  magnesite  Avhich  he  produces 
here  and  at  the  Sampson  mine  in  San  Benito  County,  Avhich  he  is 
also  operating.    This  mine  at  present  (^lay,  1925)  idle. 

Bibliography:  Reports  XII.  p.  328;  XIII,  p.  505;  XIV,  p.  275; 
XX,  pp.  26-27 ;  Bui.  38,  p.  329.  U.  S.  Geol.  Surv.,  Bull.  355, 
pp.  29-31 ;  Min.  Res.  1891,  p.  584. 

Priest  Mine.  On  the  Priest  Ranch  in  Chiles  Valley,  in  Sec.  23,  T. 
8  X.,  R.  4  W.,  M.  D.  ]M.,  13  miles  north  of  east  from  Rutherford, 
there  is  a  deposit  of  magnesite  on  which  some  development  work 
has  been  done.    Mrs.  D.  C.  Priest,  St.  Helena,  owner. 

Bibliography :  Report  XIV,  p.  275 ;  Bull.  38,  p.  328.  U.  S.  Geol. 
Surv.,  Bull.  355,  p.  31. 

Snowflake  Mine,  (see  also  under  Maltby  No.  2  Mine).  This  is  in 
Sec.  28,  T.  8  N.,  R.  4  W.,  M.  D.  'SI.,  about  two  miles  south  of  the 
old  Chiles  mill  in  Chiles  Valley.  Operated  in  connection  with  the 
Blanco  ]\Iine  (now  Tulare  Company's  mine)  for  several  years  by 
Stanley  and  Bartlett,  these  mines  began  shipments  in  1891,  and 
produced  over  1000  tons  of  magnesite  per  year  for  a  period  of  ten 
years.  Following  that  the  proi)erty  was  idle  for  more  than  20  years. 
A  vein,  striking  N.  45^  W.,  dipping  east  at  a  low  angle  near  the  sur- 
face and  steeper  below,  was  Avorked  by  an  open  cut  100  feet  long. 
It  varied  from  2'  to  7'  in  width.  In  a  tunnel  below  the  cut,  now 
caved,  it  is  reported  that  a  horse  split  the  vein  to  5'  and  2'  widths. 
Another  tunnel  opened  a  vein  about  7'  thick  which  pinched  out  both 
laterally  and  with  depth,  being  only  a  few  inches  thick  in  the  face  of 
the  drift.  At  30O'  from  the  entry,  a  50'  drift  worked  out  a  vein  or 
lens  less  than  3'  thick.  This  tunnel  is  over  500'  long,  and  probably 
produced  1000  tons.  A  third  tunnel  200  yards  northwest  of  the 
latter  is  driven  70'  northeast,  but  it  does  not  reach  the  vein.  The 
deposit  appears  to  l)e  a  continuation  of  that  on  the  Blanco  or  Tulare 
]VIining  Company's  claim. 

The  Tulare  Mining  Company  during  1917-1918  operated  tlie  Bianco 
.Mine  ad.joiiiing  the  Snowtlakc  in  Sec.  28,  T.  8  N.,  R.  4  W.,  M.  I).  M. 


56  CALIFORNIA    STATE    MINING    BUREAU. 

A  series  of  i)arallel  veins  of  luagiiesite  is  deposited  in  soft,  dark-greeii 
to  bliie-blaek  serpentine  on  the  west  side  of  Chiles  Valley.  They 
ranj^e  in  thickness  from  1'  to  6',  and  the  largest  vein  is  at  places  20' 
thick;  the  strike  is  S.  50°  E.  The  serpentine  walls  are  often  silicified 
for  several  feet  from  the  veins.  The  larger  veins  are  mixed  with 
serpentine,  and  quoting  from  Hess'  report,^ 

"they  are  locally  brecciated  and  cemented  with  less-pure  material  of  yellowish 
color,  the  original  magnesite  being  a  clear  white.  At  many  places  in  the  brecciated 
portions  each  fragment  is  covered  by  magnesite  in  radial  crystals,  forming  ii  coating 
up  to  half  an  inch  thick  and  varying  in  color  from  crystalline  clearness  to  delicate 
green  and  yellowish  green.  Cracks  in  the  serpentine  are  also  filled  with  the  same 
crystalline  magnesite." 

Samples  of  ore  analyzed  by  the  U.  S.  Geol.  Survey  ran  as  follows:  - 

Silica    (SiO^)    1.40% 

Alumina  and  ferric  oxide   (AloOf  &  Fe-jO-j) 1.96 

Lime    (CaO)    1 0.60 

Magnesia    (MgO)    45.78 

Carbon    dioxide    (CO.) 50.26 

100.00 

A  tunnel  driven  southwestward  near  the  base  of  the  hill  cut  the 
main  vein  at  800'  from  the  portal.  It  then  follows  the  vein  for  600', 
the  average  thickness  exposed  being  3'  to  4'.  In  places  it  is  stoped 
out  to  the  surface.  Several  drifts  were  run  on  smaller  veins  which 
break  off  from  the  main  vein.  Mining  was  done  by  hand  drilling. 
Thirty  men  were  employed,  (June,  1917)  the  production  being  20  to 
30  tons  daily.  When  operated  by  Stanley  and  Bartlett,  the  magnesite 
was  calcined  before  shipment,  in  a  wood-burning  kiln,  but  the  Tulare 
Company  shipped  in  the  crude  state.  It  was  hauled  12  miles  to 
Rutherford  in  motor  trucks  at  a  cost  of  $1.50  per  ton.  For  later 
operations  see  Maltby  No.  2  INIine. 

The  White  Rock  Mine  (formerly  known  as  the  Pope  Valley,  also 
Walters  Mine),  is  in  Sec.  2.  T.  9  N.,  R.  5  W.,  22  miles  hy  road  north- 
east of  Rutherford.  This  property  consisting  of  two  claims  was 
located  in  the  early  seventies,  but  no  magnesite  was  shipped  out  until 
1894.  It  was  then  worked  in  a  small  way  for  a  few  years  and  again 
lay  idle  until  it  was  taken  over  by  F.  R.  Sweasey  in  1916,  following 
which  it  developed  into  one  of  the  largest  producers  of  the  state. 
The  deposit  was  about  400  feet  above  the  level  of  Pope  Creek  on  an 
open  hillside,  bare  except  for  scattered  chamiso  brush,  and  the  bold 
white  outcrop  and  mine  dumps  could  l)e  seen  from  the  valley  below 
for  several  miles  around. 

There  were  three  groups  of  veins,  two  on  the  east  side  and  one 
on  the  west  side  of  a  small  ravine,  the  entire  group  totaling  a  width 
of  over  300  feet  on  the  surface.  The  country  rock  has  been  identified 
as  a  'serpentinized  Iherzolite'  by  Hess,^  who  described  the  deposit 
as  follows : 

"The  main  group  on  the  east  side  comprises  three  large  veins  of  magnesite  that 
can  be  definitely  traced  for  distances  of  about  140,  250  and  230  feet,  with  strikes 
N.  28°,  30°  and  45°  W.,  respectively.  At  their  north  ends  the  western  and  eastern 
veins  are  but  thirty  feet  apart,  and  the  middle  vein  probably  converges  with  the 
eastern  one. 

"Longitudinal  faults  occur  in  both  of  the  outer  veins.  Between  the  large  veins 
are    many    smaller   ones    having   a    general   parallelism    to    the   main   bodies.      At   its 

1  Hess,  F.  L.,  Magnesite  deposits  of  California;  U.  S.  Geol.  Surv.,  Bull.  355, 
p.  30,   1908. 

2  Authority,  W.  Nichilini,  foreman,   1918. 
2  Op.  cit.,  p.  28. 


MAGNESITE    IX    CALIFORNIA.  57 

widest  exposure,  the  western  vein  is  about  ten  feet  thick,  of  which  about  five 
feet  on  the  footwall  is  solid  white  magnesite,  althougli  tlie  upper  five  feet  on  the 
hanging  wall  side  contains  many  inclusions  of  serpentine.  The  structure  of  the 
eastern  vein  is  similar  and  in  places  the  magnesite  may  be  seen  grading  into  the 
country  rock  ;  it  is  about  twelve  feet  wide  where  exposed  in  a  shallow  crosscut. 
In  the  middle  vein  a  width  of  eighteen  inches  to  five  feet  of  clear  white  magnesite 
is  exposed.  There  has  been  some  crushing  of  the  magnesite  and  the  broken  particles 
have  been  cemented  witli  yellowish  less-pure  material.  Part  of  the  magnesite  has 
formed  in  yellow  botryoidal  masses  that  are  rather  impure.  Some  crystalline 
magnesite  similar  to  that  of  Chiles  Valley  is  found   in   the   crevices. 

"A  second  group  with  a  moie  northerly  strike  lies  100  feet  or  more  above  the 
veins  just  descriljed.  The  veins  forming  this'  group  are  smaller,  running  from 
two  inches  to  two  feet  in  width,  and  tlie  larger  of  these  are  impure. 

"On  the  west  side  of  the  ravine.  200  to  250  feet  from  the  veins  first  described,  is 
a  third  group  with  a  strike  between  north  and  northwest.  The  largest  vein  is  four 
to  six  feet  wide,  and   seven  otliers  from  one  to  two  feet  wide  occur  within   12.5   feet." 

Practically  all  miiiiny  was  confined  to  the  main  group  on  the  east 
side  of  the  ravine.  Here,  a  large  open  cut  was  run  in  on  the 
e-roppings  for  about  250  feet.    Fifty  feet  below  this  cut  a  tunnel  was 


Photo  Xo.   16 — White  Rock  Mine  in  Pope  Valley,  Xapa  County. 
Photo  by  F.  R.   Sweasey. 

driven  across  several  small  veins,  cutting  the  main  orebody  at  120 
feet.  Drifts  were  run  botli  north  and  south  along  the  vein.  There 
are  three  stopes  in  tiie  north  drift,  each  30  feet  or  more  in  length,  and 
one  in  the  south  drift.  Stoping  was  carried  up  to  the  surface, 
the  vein  varying  from  10'  to  30'  wide.  A  main  working  tunnel  in 
over  450  feet  long,  was  driven  to  strike  the  orebody  100  feet  below 
the  upper  tunnel.  At  290  feet  from  the  portal,  the  vein  was  encoun- 
tered. Drifts  were  made  at  75-ft.  intervals  and  raises  driven  to 
connect  with  the  upper  tunnel  so  that  all  of  the  ore  mined  could  be 
handled  through  this  adit.  It  was  estimated  by  the  operators  (July, 
1917)  that,  there  was  exposed  in  these  workings  in  excess  of  100,000 
tons  of  magnesite.  Eight  air  drills  were  u.sed  in  the  mine,  power 
being  supplied  l)y  a  45  li.  p.  Diesel-type  combined  engine  and  air 
compressor. 

An  aerial  tramway  4200  feet  in  length  conveyed  the  ore  from  the 
mine  to  a  calcining  plant  alongside  of  the  county  road.  When  visited 
in  1917  there  were  five  10-ton-capacity  stack  kilns;  following  which 


58  CALIFORNIA    STATE    MINING   BUREAU. 

six  additional  kilns  were  constructed  and  the  daily  production 
greatly  increased.  Coke  fuel  Avas  used.  A  portion  of  the  output 
was  calcined  at  a  small  plant  at  Rutherford,  to  which  it  was  hauled 
in  motor  trucks  at  a  cost  of  $3  per  ton  crude  ($4  in  1922).  Forty 
men  Avere  employed  at  the  property,  the  production  being  100  tons 
daily. 

Following'  the  death  of  F.  E.  Sweasey,  owner,  this  mine  was 
operated  by  C.  S.  INIaltby  of  San  Francisco,  under  lease  during  1921- 
1922,  but  closed  down  in  May,  1923,  the  movable  equipment  being 
transferred  to  the  Blanco  mine  in  Chiles  Valley.  It  is  stated  that 
the  orebodies  of  the  AYhite  Rock  mine  "were  bottomed  at  a  depth  of 
300  feet  below  the  outcrop. 

Bibliography:  Cal.   State  Min.  Bur.  Reports  XIV,  p.  274;  XX, 
p.  27 ;  Bull.  38,  p.  330.    U.  S.  Geol.  Surv.,  Bull.  355,  p.  28. 


Photo  No.    17 — Calcining  plant  of  the    White  K<k-1-l  Mine  in   Pope  Valley,  Napa 
County.     Photo  by  F.  R.  Sweasey. 

NEVADA  COUNTY. 

Magnesite  has  been  found  in  the  serpentine  areas  of  the  Sierras, 
as  well  as  in  the  Coast  Ranges,  but  in  the  'Mother  Lode'  and  other, 
northern  Sierran  counties  the  occurrences  are  mostly  of  minor 
importance  only  and  of  doubtful  commercial  value. 

Nevada  City.  It  is  noted  by  Eakle  ^  as  "narrow  veins  *  *  * 
in  the  serpentine  at  Nevada  City." 

Sec.  22,  T.  16  N.,  R.  8  E.,  :\T.  D.  M.  In  this  locality,  one  mile  north 
of  Grass  Valley,  H.  C.  Schroeder,  Nevada  County  assessor,  reports 
the  occurrence  of  a  mineral  said  to  l)e  magnesite,  outcropping  as 
small  stringers. 


Eakle,  A.  S.,  Minerals  of  California:   Cal.   State  Min.   Bur.,   Bull.   67,  p.   93,   1914. 


MAGNESITE    IN    CALIFORNIA.  59 

PLACER  COUNTY. 

Although  reported  to  oceur  at  a  number  of  localities  in  Placer 
County,  it  is  evident  that  but  few  of  the  known  niagnesite  deposits 
have  i»een  considered  worthy  of  development.  Eakle  ^  states  that 
"veins  occur  near  Damascus  and  ^Michigan  Bluft'  and  at  Gold  Run." 
Other  general  localities  as  noted  by  Waring,-  are  "in  serpentine  area, 
5  miles  northeast  of  Iowa  Hill,  in  Canon  Creek,  ^  mile  south  of  Towle, 
and  on  the  south  slope  of  Bear  River,  2^  miles  north  of  Towle." 

Little  Bear  magnesite  mine.  This  property  is  situated  in  the  SE^, 
See.  .S5,  T.  16  N.,  R.  10  E..  M.  D.  M.,  above  the  Alta  Power  House. 
The  Little  Bear  River  furnishes  a  water  supply.  According  to  R.  W. 
Stone  of  the  U.  S.  Geol.  Survey,  there  is  said  to  be  a  2-^-foot  vein  of 
magnesite  in  serpentine,  upon  which  assessment  work  only  has  been 
done.  Not  enough  ore  was  found  to  make  a  shipment.  Owned  by 
Arthur  Lee,  Towde  post  office. 

Placer  County  Properties  Co.  (formerly  the  Sprague-Keasby 
Asbestos  and  Magnesia  Co.),  holds  -100  acres  in  claims  in  Sec.  13,  T. 
15  N.,  R.  10  E.,  and  in  Sees.  7  and  18,  T.  15  N.,  R.  11  E.,  M.  D.  M. 

A  description  of  the  property  by  Waring  ^  is  referred  to  for  the 
following  notes :  A  tunnel  originally  undertaken  in  the  search  for 
gold-bearing  gravels  has  exposed  a  network  of  narrow  magnesite 
veins  at  considerable  deptli,  but  further  development  will  be  neces- 
sary to  determine  the  value  of  the  deposit.  There  is  an  abundance 
of  timber  and  water  at  the  property.  On  the  other  hand,  the  product 
would  have  to  be  hauled  30  miles  to  Colfax,  to  reach  the  railroad. 
The  officers  of  the  Placer  County  Properties  Co.  are :  S.  M.  Sprague, 
president.  East  Auburn :  ]Mrs.  Gertrude  Shelley,  secretary,  326 
Ochsncr  Bldg..  Sacramento. 

Bibliogniphij:  Cal.  State  Min.  Bur..  Report  XV,  pp.  391-392. 
U.  S.  Geol.  Surv.,  Bull.  540,  pp.  501-503;  :\rin.  Res.  of  the 
U.  S..  1914.  Part  IL  p.  579. 

Sullivan  et  al.  This  property,  from  which  a  small  shipment  was 
made  in  1916,  is  located  in  the  Dutch  Flat  Mining  District,  in  the 
N^  and  NE^  of  Sec.  19,  T.  16  N.,  R.  11  E.,  M.  D.  M.  The  deposit  is 
on  80  acres  purchased  from  the  Central  Pacific  Railroad  and  patented. 
The  surface  is  rugged  and  the  holdings  lie  at  an  elevation  of 
4000  feet.  The  nearest  town,  Alta,  is  on  the  railroad.  It  can  be 
reached  fi-om  the  mine  by  four  miles  of  road  and  trail.  Post  office  at 
Dutch  Flat. 

Yellow  pine  timber  grows  on  the  property,  and  water  from  a 
branch  of  Bear  River  is  available.  The  magnesite  occurs  in  the  usual 
form,  as  veins  in  serpentine  rock.  These  have  been  opened  by  tunnels. 
On  the  south  side  of  a  ravine  an  80-foot  tunnel  followed  a  4-foot 
vein  for  about  50  feet,  and  now  shows  stringers  from  6  inches  to  2 


'  KiikU'.  A.  S.,  Cal.  State  Min.  Bur.,  Bull.  No.  67,  p.  93.  1914. 

-  W;iring,  C.  A.,  Mines  and  mineral  resources  of  El  Dorado  et  al.  counties:  Chap- 
tiTs  of  State  Mineralogist's  Report,  biennial  period  1915-1916,  Cal.  State  Min.  Bur., 
p.    121,    1916:   also  Report  XV.   p.   ;591. 

'Op.  cit.,  pp.   121-122;  also  Report  XV,  i)p.  :iyl-392. 


60  CALIFORNIA    STATE    MINING   BUREAU. 

feet  wide.  On  the  same  side,  an  incline  70  feet  in  length  also  shows 
stringers.  About  10  tons  of  high-grade  ore  was  on  the  dump.  On 
the  north  side  of  the  ravine,  no  ore  was  encountered  in  a  160-foot 
tunnel,  driven  north. 

One  shipment  of  40  tons  of  98.5%  MgCO;,  ore,  which  all  came  from 
a  40-foot  E.-W.  open  cut  and  tunnel,  was  made  in  1916. 

The  owners  of  the  mine  are  D.  J.  Sullivan  of  Dutch  Flat  and  W.  F. 
Hemphill  and  R.  E.  Noble  of  Roseville. 

Towle  deposits.  Outcrops  of  magnesite  in  the  region  of  Towle 
occur  in  brecciated  serpentine.  An  outcrop  is  reported  in  Sec.  6,  T. 
15  N.,  R.  11  E.,  M.  D.  M.,  and  one  each  in  Sees.  24  and  36,  T.  16  N., 
R.  10  E.  No  development  work  has  been  done  on  any  of  these 
deposits. 

Owned  by  J.  H.  Johnson  of  East  Auburn,  and  J.  D.  Sullivan  of 
Towle. 

Bihliography :  Cal.  State  Min.  Bur..  Mines  &  Mineral  Resources, 
Placer  Co.,  1916;  also  Report  XV,  p.  892.  U.  S.  Geol.  Surv., 
Min.  Res.  of  the  U.  S.,  1914,  Part  II,  p.  579. 


MAGNESITE   IN    CAT.IFORNIA. 


61 


RIVERSIDE  COUNTY. 

The  chief  deposit  of  inag-nesite  in  Riverside  County  is  near  AVin- 
chester.  This  in-operty  now  known  as  the  Hemet  Magnesite  Mine, 
has  been  fully  deseribed  by  Hess,'  supphMiiented  hitcr  by  (iale,-  who 
says  in  part : 


Photo  No.    18 — Stockwork  df  magiiesite  veins  in  open   cut  at 

Hemet  Magnt-site  Mine.  The  veins  vary  from  },"  to  about 

1"    in    thickness.      Tlie  wliole    faee    is    mined    and    tlie 

magnesite    hand-sorted  on    a    picking    belt.       Plioto    by 
C.  A.  Waring. 

"The   magnesite  mined  at   WinchesteH'  is  derived   from  deeply   decomposed  serpen- 
tine   rock,    which    is    found    at    the    crest  of    one    of    the    steep    peaks    that    form    the 


'  Hess,  F.  L..  Magnesite  deposits  of  California  :  U.  S.  Geol.  Surv.,  Bull.  355,  pp.  38-39. 
=  fJale,  H.  S.,  Magnesite  deposits  in  California  and  Nevada:   U.  S.  Geol.  Surv.,  Bull. 

.li>,  pp.  516-519. 


62  CALIFORNIA    STATE    MINING    BUREAU. 

divide  tjetweon  tlie  valley  in  whicli  the  town  of  Wiiicliester  is  situated  and  Diamond 
Valley,  on  the  south.  The  mine  is  aliout  two  miles  in  an  air  line  from  the  nearest 
point  on  the  railroad  and  is  four  miles  by  g-nod  road  from  the  shipping  point  at 
Winchester.  *  *  *  The  open  cut  of  the  magnesite  mine  is  about  500  feet  above 
the  level  of  the  plain  at  the  vallev  margin.  *  *  *  iphe  property  all  lies  within 
the  NW.^  of  See.  31,  T.  5  S.,  R.   1   W.,   S.  B.   M. 

"The  area  is  g'eolog'ically  somewhat  complex.  It  consists  essentially  of  dark 
banded  micaceous  gneisses  and  schists  in  which  the  foliation  trends  in  general  from 
northwest  to  southeast,  and  dips  steeply  to  the  northeast.  *  *  *  Probably 
Intrusive  into  the  micaceous  .gneiss  is  a  belt  of  serpentine  from  200  to  perhaps 
400  yards  wide,  extending  in  a  northwest-southeast  course  from  a  point  near  the 
northwest  corner  of  the  section.      *      *     * 

"Many  pits  on  this  property  expose  networks  of  thin  veins  of  magnesite  in 
serpentine  rock  decomposed  in  place.  The  principal  deposit  of  this  sort  is  that 
shown  in  a  large  open  cut  crossing  the  summit  of  tlie  ridge  at  its  north  end  and 
making  a  prominent  landmark  visible  for  miles  through  the  valley  on  the  north. 
This  cut  is  about  85  yards  long  and  some  2  5  yards  wide  at  its  widest  place  and  is 
entrenched  to  a  depth  of  60  to  75  feet  in  the  crest  of  the  ridge.  Dumps  have  been 
thrown  out  at  both  ends  and  from  this  cut  all  the  magnesite  shipped  has  been 
taken  out.  The  cut  shows  a  network  of  magnesite  veins  throughout,  these  being 
fully  as  numerous  and  of  as  great  individual  thickness  at  the  present  bottom 
of  the  pit  as  they  were  near  the  top,  or  possibly  the  size  and  thickness  of  the 
veins  are  even  increasing  with  depth." 

An  analysis  of  a  representative  sample  of  the  material  as  mined, 
made  up  of  thirty  portions  collected  in  various  parts  of  the  cut,  is 
given  by  Gale  ^  as  follows : 

SiO.    6.17% 

AlO,    Fe..O,,    .80% 

Cab    Trace 

MgO 4  3.80% 

CO. 45.02% 

Undetermined     4.14% 

100.00% 

Quoting  further  from  the  same  author : 

"The  following  average  taken  from  a  mill  run  shows  the  composition  of  the 
product  ground  for  plastic  use,  as  it  is  barreled  for  shipment.      *      *      * 

Insoluljle 14.00% 

Iron   and   Alumina .80% 

Calcium    Oxide    .61% 

Magnesium  Oxide S4.'59% 

100.00% 

"The  recoverable  and  available  magnesite  veins  possibly  constitute  one-tenth  of 
the  mass,  although  the  actual  proportion  of  magnesite  in  the  finer  form  may  be 
considerably  highei".  Thus  eight  to  ten  or  more  wheelbarrow  loads  of  waste  go 
over  the  dump  for  one  load  of  magnesite  saved.  There  is  much  fine  magnesite  in 
the  dump,  and  it  has  been  suggested  by  the  owners  that  this  might  be  utilized 
directly   in  the  manufacture  of  brick.      *      *      * 

"The  deposit  at  Wincliester  presents  several  features  that  might  be  considered 
almost  unique.  In  tlie  first  place  the  rather  exceptionally  favorable  situation  of 
the  deposit  for  mining,  and  also  for  shipment,  gives  to  it  a  distinct  advantage. 
In  many  other  situations  it  would  doubtless  be  impracticable  to  mine,  separate,  and 
ship  magnesite  occurring  in  a  network  of  thin  veins  traversing  a  massive  body  of 
serpentinous  rock.  As  stated,  the  whole  mass  is  so  deeply  weather-decayed  that 
it  breaks  down  easily  and  is  mined  by  open  cuts  with  some  blasting,  the  ore  and 
waste  being  worked  over  by  liand  labor,  with  pick,  shovel  and  wheelbarrow.  How- 
ever, the  magnesite  readily  separates  from  the  much  decomposed  country  rock, 
crumbling  away  as  dug,  leaving  the  fragments  comparatively  clean  to  be  sorted  by 
hand.  *  *  *  xhe  situation  of  the  deposit  at  the  crest  of  a  steep  slope  is  an 
important  factor,  as  it  affords  a  ready  dump  for  waste  and  convenient  sites  for 
ore  chutes  and  loading  bins.     The  mining  methods  are  therefore  of  the  simplest  type." 

The  same  author  mentions  that  "the  entire  product  of  the  mine 
at  Winchester  is  manufactured  into  cement  or  is  sintered  for  furnace 
use  at  the  company's  plant  in  Los  Angeles." 

The  report  from  which  the  above  excerpts  are  taken  was  made  in 
1912.  Since  then  the  Hemet  magnesite  mine  has  been  under  the 
control  of  a  number  of  ditferent  parties.  Extensive  development 
work  has  been  carried  on  and  a  new  and  complete  calcining  and 
grinding   plant   has   been   erected   at   the   mine   to    replace   the    Los 

3  Op.  cit.,  p.  51S. 


MAGNESITE    IN    CAIJFORNIA. 


63 


Angeles  plant,  which  was  abandoned.  Mining  is  done  by  open  cut 
and  glory  hole.  A  tunnel  has  l)een  driven  N.  60°  E.  in  the  main 
quarry  floor   to   cut   the   deposit   through   drifts   along   the   orebody 


Photo  No.  19 — General  \ie\v  of  the  lit-uiei  Magno.siio  ^Nline  luuking  westward 
from  the  top  of  the  hill  across  the  Hemet  Valley.  Riverside  County.  The 
large  open  cut  at  extreme  right  shows  stockwork  of  magnesite  veins 
throughout  its  length.  The  calcining  and  crushing  plant  is  housed  hi 
the  building  below  the  tramway.     Photo  by  C.  A.  Waring. 


Photo  No.  20 — Hemet  Magnesite  Mine  looking  eastward,  showing  dumps,  and  sort- 
ing and  washing  plant  at  head  of  400-ft.  gravity  tramway  which  conveys  the 
ore  to  the  calcining  plant.     Photo  by  C.  A.  Waring. 

running  N.  40°  "VV.  The  south  drift  connects  by  a  chute  with  the 
glory  hole  50  ft.  below  the  toj),  and  a  raise  in  the  nortli  drift  has 
been  put  up  to  tap  the  glory  hole.  The  latter  gives  backs  of  7')  ft. 
Drifting  will  be  continued  southeast  to  determine  the  length  of  the 
orebody.  It  was  the  intention  of  the  operators  to  glory-liolc  Hie 
entire  top  of  the  hill.    Black  powder  was  used  for  blasting. 


64 


CALIFORNIA    STATE    MINING   BUREAU. 


Surface  equipment  includes  iiieclianical  conveyors,  screens,  washers, 
a  6'  X  60'  rotary  kiln,  grinders  and  packing  house. 

The  ore  is  first  carried  hy  a  system  of  belt  conveyors  to  a  sorting 
room  containing  a  picking  belt  '>W  long  by  3'  wide.  TAvelve  pickers 
are  employed  and  each  sorts  out  about  1500  lbs.  of  magnesite  per 
shift.  The  material  is  then  conveyed  to  a  screen  where  it  is  washed 
and  the  fines  rejected.  AVater  for  washing  is  pumped  from  the  valley 
below  the  mine.  All  material  passing  through  4-inch  openings  is 
rejected  as  it  is  impossible  to  hand  sort  the  finer  stuff.  The  washed 
and  screened  magnesite  is  burned  in  the  6'  x  60'  rotarv  calciner  and 


Photo  No.  21 — Outcrop  of  INIagnesite  at  tlie 
Sampson  Magnesite  Mine.  San  Benito 
County.  An  idea  of  its  size  may  be 
gained  from  tlie  standing  figures.  Plioto 
by  John  D.  Hoff. 

then  distributed  to  cooling  bins  by  a  drag  conveyor.  It  is  finally 
ground  in  Sturtevant  buhr-emery  mills  to  pass  100-mesh  and  packed 
for  shipment. 

It  may  be  noted  here  that  no  mechanical  means  for  concentrating 
the  magnesite  or  effecting  a  separation  of  the  mineral  from  the 
waste  rock  has  so  far  been  found.  Various  tests,  including  electro- 
magnetic separating  machines,  did  not  prove  successful,  and  as 
hand  picking  or  sorting  must  necessarily  be  used  a  great  deal  of  the 
finer  magnesite  has  to  be  thrown  on  the  dump  Avith  the  Avaste. 


MAGNESITE   IN    CALIFORNIA.  65 

Daily  production  was  30  tons,  of  calcined  magnesite  per  24  hours, 
being  the  capacity  of  the  kiln.  Electric  power  is  used.  A  total  of 
•'!.■)  men  were  employed,  at  the  time  the  property  Avas  visited. 

The  Hemet  magnesite  mine  was  last  operated  hy  the  Welman- 
Lewis  Co.,  Hibernian  Bank  Kklg.,  J^os  Angeles,  for  Innes-Speiden 
&  Co.,  Inc.,  of  New  York,  lessees;  but  there  has  been  no  production 
since  1919.    INIagnesco  Refractory  Company,  owner,  Los  Angeles. 

Bibliography:  Cal.  State  Min.  Bur.,  Reports  XV,  p.  579;  XVII, 
pp.  327-328.  IT.  S.  Geol.  Surv.,  Bull.  355,  pp.  38-39 ;  Bull.  540, 
pp.  516-519. 


6—39802 


66 


CALIFORNIA    STATE    MINING   BTTREAU. 


SAN    BENITO    COUNTY. 

Bonanza  Quicksilver  Mine.  The  occurrence  of  magnesite  is 
reported  on  the  claims  of  this  quicksilver  group,  in  Sec.  29,  T.  18  S., 
R.  12  E.,  U.  D.  M.  near  Hernandez.    Undeveloped. 

Maltby  No.  3  Mine  (see  Sampson  Mine). 

Jerome  Magnesite  Group  (sec  Standard  Group). 

Sampson  Magnesite  Mine  (Maltby  No.  3  Mine).  This  property 
comprises  a  group  of  21  claims,  of  which  three  had  been  patented 
and  three  were  in  process  of  patenting  in  October,  1917.  The  mine 
lies  in  Sees.  34,  35  and  36,  T.  17  S.,  R.  11  E.,  M.  D.  M.,  40  miles  by 
road  west  of  Mendota.  the  nearest  railroad  station.  The  magnesite 
occurs  on  the  summit  of  a  high  spur  running  westerly  from  Sampson 


Photo  Xo.   22- 


-South  open-cut  of  Sampson  Magnesite  Mine.     Octobei-   2,   1917, 
before  installation  of  aerial  tram. 


Peak,  and  lying  between  two  forks  of  Larious  Creek  at  an  elevation 
of  3900  feet.  The  outcrop  of  the  principal  body  originally  covered 
from  two  to  three  acres  and  consisted  of  massive  crags  of  white 
magnesite  (see  Photo  No.  21),  which  have  since  been  quarried  off. 
It  is  500'  in  length  and  appears  to  strike  N.  70°  E.  Gale  ^  in  his 
report  on  this  property  said:  "If  the  deposit  continues  in  depth  with 
horizontal  dimensions  corresponding  to  those  at  the  surface,  it  is  of 
immense  size."  Numerous  small  croppings  are  found  on  the  ridge 
below  the  main  deposit. 

The  orebody  was  early  worked  in  two  main  open  cuts.  The  'North 
Cut'  when  visited  in  October,  1917,  was  approximately  25'  high,  and 
50'  deep,  with  the  magnesite  showing  in  a  less  shattered  condition 

'Gale,  H.  S.,  Magnesite  deposits  in  California  and  Nevada:  U.  S.  Geol.  Surv.. 
Bull.  540,  page  505,   1914. 


MAGNESITE   IN    CAIJPORNIA. 


67 


Photo  No.  2  3 — Quarries  and  ore-bins  of  Sampson  Magnesite  Mine,   taken   fi'om 
aerial  tram,  November  8,  1923. 


I'lioTo    No.    21 — Main    ■ji.  n  lut    at    Sampson    (.Maltb.\    No.    3)    Magnesite   Mine, 
near   New    Idi-ia.    San    Henito   County,   November,    1923. 


68 


CALIFORNIA    STATE    MINING   BUREAU. 


than  nearer  the  snrfaee.  Tlie  'South  ("uf  (see  Plioto  No.  22)  was  on 
the  southerly  side  of  the  ridge  opposite  the  North  Cut.  In  October, 
1917,  the  ore  was  being  hauled  in  four-horse  wagons  about  a  mile 
down  a  rather  steep  road  to  the  calcining  kilns  (see  Photo  No.  25) 
in  the  canon  of  Larious  Creek.  Later,  an  aerial  tram  M^as  installed. 
Three  vertical  kilns  were  built  in  1917,  Avith  an  average  capacity 
of  16  tons  of  calcined  magnesite  each,  per  24  hours.  Later  three 
more  were  added.  Crude  oil  was  used  for  fuel,  and  it  is  stated 
that  less  than  1  bbl.  was  consumed  per  ton  of  calcined  magnesite 
produced.  As  may  be  noted  from  the  photograph  (No.  25)  these 
furnaces  were  much  shorter  than  the  shaft-kilns  usually  built  for 
calcining  magnesite.  No.  1  furnace  (nearest  to  the  camera)  was  7 
ft.  in  diameter.  No.  2,  6'  6"  diam.  and  No.  3,  6'  diam.     The  interior 


Photo  No.   25 — Calcining  magnesite  in  vertical  kilns,   at  Sampson   Mine, 

October,  1917. 


fire-box  construction  is  shown  in  Photo  No.  26.  They  were  built  of 
common  brick,  lined  with  fire-brick;  and  equipped  with  6  burners 
to  each  kiln.  Air  atomizers  were  used,  the  air  being  supplied  by  a 
blower  driven  by  a  distillate  engine.  There  was  a  duplicate  blower- 
set  for  use  in  case  of  a  break-down. 

Up  to  September  25,  1917,  something  over  1000  tons  of  calcined 
material  had  been  shipped,  stated  to  average  less  than  3|%  SiOa; 
2|%  CaO;  2%  CO.;  and  between  2%  and  3%  Fe^O^.  Analyses  of 
the  first  two  carloads  of  the  cnlcined  magnesite  shipped  are  given 
as  follows : 

No.  1 


SiOa     1-17% 

Fe  and  Al 1.20% 

CaO 1-99% 

MgO    91.60% 

Ignition   loss   3.85% 


No.  2 
1.76% 
1.94% 
2.00% 
92.16% 
2.14% 


MAGNESITE   IX    CALIFORNIA. 


69 


Photo   No.    26 — Interior   of   vertical   magneslte-calcining   furnace  of   Hoff-Price 
Company,  at  Sampson  Mine,  under  construction,   October   2,   1917. 


[^-  »VU. 


I'HOTO    X' 


27 — Caleiniiii;  il  i  III  i,{   Milii;.    ,\..    :;    (Sampson)   Miikh' site  Mine,  i>ro- 
liucing  dead-burufd   refraelory  nmgnesite,   November,    iy2o. 


70 


CALIFORNIA    STATE    MINING    BUREAU. 


Tile  material  was  hauled  in  motor  trucks  to  the  railroad  at 
Mendota,  (some  has  l)een  sent  via  Tres  Finos),  at  a  cost  of  $7  per  ton. 

In  October,  1917,  there  were  75  men  on  the  pay-roll.  The  furnaces 
were  operated  by  three  8-hour  shifts,  and  the  mine  by  a  day-shift 
crew  only. 

This  mine,  the  past  tlii-ee  years,  has  been  operated  under  lease 
by  C.  S.  ]\Ialtl)y.  The  six  vertical  kilns  formerly  in  use  at  this  mine 
have  ])een  replaced  by  a  rotary  furnace  7'  by  80'  (see  photo),  operat- 
ing at  li  minutes  per  revolution.  It  is  oil-fired  and  Avhen  last  visited 
by  the  writer  (in  November,  1928)  was  producing  85  tons  of  dead- 
burned  refractory  magnesite  per  24  hours.  From  45  to  50  men  are 
employed.  The  ore  is  crushed'  to  ^-inch  mesh  before  charging  and 
2^  tons  of  crude  ore  are  required  for  1  ton  of  calcined.  Steam  power 
is  used.     Fuel  oil  is  obtained  from  the  pipe  line  of  the  Associated 


Photo  No.  2S — Rotary  kiln  at  Maltby  No.  3   (Sampson)  Magne.site  Mine, 
San   Benito   County. 

Oil  Company  at  IMendota,  there  being  a  pumping  station  on  the  line 
at  that  point.  The  calcined  ore  is  hauled  by  trucks  to  the  railroad 
at  Mendota.  As  the  orebody  is  on  top  of  a  ridge,  the  ore  is  broken 
by  quarrying  operations,  and  carried  to  the  furnace  by  a  Painter 
aerial  tram,  5000  feet  in  length,  having  16  buckets  and  being  gravity 
operated.  Jack-hammer  drills  are  used  in  the  quarry.  The  com- 
pressor is  driven  by  a  4-cylinder  gasoline  engine  which  formerly 
did  duty  in  a  Packard  automobile. 

A  chemical  lal)oratory  is  maintained  at  the  mine,  for  technical 
control  of  the  furnace  i)roduct.  Analyses  are  daily  made  for  SiO^, 
CaO,  loss  on  ignition,  and  for  Fe^.Oa  -|-  ALO..  +  MnO.  combined. 

In  1924,  a  selected  portion  of  the  product  of  the  mine  was  caustic 
calcined  for  plastic  purposes. 


MAGNESITE   IN    CALIFORNIA.  71 

Tlie  Sami)soii  iiiagnesite  mine  is  owned  by  R.  H.  Moore,  Hugo 
Fischl  and  Alex.  Morrison,  Sharon  Bldg.,  San  Francisco.  It  is  under 
lease  to  C.  S.  Maltby,  Humboldt  Bank  Bldg.,  San  Francisco. 

Bibliography:  Cal.  State  Min.  Bur.,  Reports  XV,  pp.  643-645; 
XVIIT,  pp.  218-219;  XIX.  p.  26;  XX  p.  28.  U.  S.  Geol.  Surv., 
Bull.  355,  p.  38;  Bull.  540.  pp.  503-50!);  Bull.  603,  p.  208;  Min. 
Res.  of  U.  S.,  1911,  Pt.  II,  p.  1120. 

Standard  Group  (includes  Jerome  and  other  claims).  This  group 
of  8  claims  was  located  in  1917,  by  Hugo  Fischl,  HoUister,  in  Sees. 
35  and  36,  T.  17  S.,  R.  11  E.,  M.  "D.  M.,  southeast  of  the  Sampson 
Group.  The  outcrop  is  stated  to  be  traceable  for  3500  feet  in  length. 
Magnesite  is  found  over  a  width  of  50'-60',  though  it  is  not  all  ore. 
In  October  of  that  year,  four  men  were  working  on  development. 
Samples  of  the  magnesite  submitted  were  of  good  quality.  There  is 
also  a  large  body  of  hydro-ma gnesite. 

The  group  is  4  miles  from  Idria  by  a  wagon  road  formerly  used  by 
the  New  Idria  Quicksilver  Company  for  getting  out  timber.  In 
1924,  the  claims  were  taken  over  by  H.  A.  Palmer  et  al,  of  Holly- 
wood, and  the  Superior  Magnesite  Company  organized.  A  road 
has  been  built  from  Hernandez  to  the  group,  making  it  35  miles  to 
Coalinga  and  38  miles  to  Kings  City.  Machinery  has  been  hauled 
in  and  is  now  (July,  1925)  being  installed. 


72 


CALIFORNIA    STATE    MINING   BUREAU, 


SAN  BERNARDINO  COUNTY. 
Afton   Magnesite   Deposit.     A   deposit   of   magiiesite   of   unusual 
size  has  been  discovered  about  one  and  a  half  miles  east  of  Afton 
station  on  the  Los  Angeles  and  Salt  Lake  Railroad.     It  lies  1900 


PT.ATE    VI. 


feet  by  actual  survey  southeasterly  of  the  railroad,  thus  being  very 
accessible  to  shipping  facilities.  The  deposit  has  been  covered 
])y  three  lode  locations,  namely:  Cliff  Side,  Hill  Top,  and  Crown 
claims.  It  is  owned  by  the  Cliffside  Magnesite  Company,  John  M. 
Nordheim,  president,  518  West  41st  Place,  Los  Angeles, 'and  W.  J. 
Swan,  secretary,  San  Bernardino. 


MAONESITE    IN    CALIFORNIA. 


78 


Tlie  inaunt^site  on  the  Clitt'  Side  claim  (see  sketch  map)  outcrops 
as  a  bold  white  ledge  striking  easterly  over  a  precipitous  ridge  which 
rises  abruptly  out  of  the  Mojave  River  bed  to  an  elevation  of  500 
feet  above  the  river.  The  magnesite  ledge  is  exposed  for  about 
•400  feet  from  the  base  to  the  top  of  the  croppings  and  it  forms  a 
striking  landmark  visible,  for  several  miles  west  of  the  deposit,  as 
I  is  shown  in  Photo  Xo.  29. 


Phot"  X".  :j:i--:\Iagiifsite  outcrop  un  the  Cliff  ;-ide  Claim  near  Afton,  S;in  Ber- 
nardino County.  This  cropping  continuous  for  about  4  00  feet.  Photo  by 
C.  A.  Waring. 


i'HuTu  No.    :i'i Aii< 


Photo   by  C.   A.   Warint?. 


>p  un  the  Hill  Top  tUaim. 


Near  the  top  of  the  croppings  a  slide  has  denuded  it,  showing  a 
thickness  of  a  couple  of  hundred  feet  and  dip  of  40^  northward 
towards  tlie  rivei-.  At  least  1000  tons  of  ore  are  exposed  at  this  place. 
The  magni'sitc  underlies  a  soft,  red-colored,  decomposed,  conglom- 
t  rate  material  with  which  it  forms  a  striking  coloi'  contrast.  This 
conglomerate  bed  is  several  hundred  feet  thick  and  is  superimposed 


74 


CALIFORNIA    STATE    MINING   BUREAU. 


by  a  massive  bed  of  fine-grained  gray  sandstone,  wliose  dip  is  eon- 
formable  to  that  of  the  magnesite.  Most  of  the  sandstone  has  been 
eroded,  so  that  it  only  outcrops  in  one  place.  Underlying  the  magne- 
site are  decomposed  sandstones  and  dark,  slaty  shales. 

The  magnesite  varies  in  color  from  pinkish  to  grayish  white 
and  pure  white.  Near  the  hanging  M^all,  it  is  deposited  in  nodular 
form,  the  individual  nodules  vary  from  egg  size  to  boulders  of  several 
inches  diameter.  Nearer  the  footwall  it  is  more  compact  and 
stratified,  varying  from  massive  to  thinly  laminated.  Occasional 
seams  of  silica  occur  interbedded  with  shaly  magnesite  in  the  foot- 
wall. 


I 


Photo  No.  31 — Magnesite  exposure  on  the  Qviaker  Group 
southeast  of  Cima,  San  Bernardino  County.  Photo 
by  Geo.  W.  Elder. 

Analyses  of  samples  taken  from  three  places  along  the  outcrop 
spaced  20  feet  apart  are  given  by  W.  J.  Swan,  as  follows : 

No.  1          No.  2  No.  3 
Per  cent  Per  cent  Per  cent 

Silica   (SiO-.)    10.14          10.12  10.10 

Alumina    (AI2O3)    -- 4.40            3.69  1.73 

Iron   (FegOa)    0.7S            0.67  1.41 

Lime    (CaO)    1.74             3.36  3.10 

Magnesia   (MgO)    36.48          35.62  38.19 

Alkalies     0.S6            O.SS  

Carbon  Dioxide    (OO2) 45.68          45.80  40.65 

Analysts:  Nos.   1  and  2— Smith,   Emery  &  Co.;  No.   3— Sill  and   Sill. 


MAGXESITE    IX    CALIFORNIA. 


75 


On  the  Hill  Top  Claim  (see  Photo  No.  30),  erosion  of  the  overlying 
sediments  has  nneovered  a  large  body  on  the  hillside,  which  at  the 
surface  is  rather  soft,  due  to  exposure.  A  good  idea  of  the  size  of 
this  body  may  be  obtained  by  comparing  it  with  the  discovery 
monument  slioAvn  in  the  photograph,  directly  above  it. 

Very  little  work  has  ])een  done  at  the  claims  other  than  some 
stripping  of  the  overburden  on  the  Cliff  Side  claim.  AV.  J.  Swan 
and  associates  have  erected  an  aerial  tramway  from  the  base  of 
the  cropping  on  the  Cliff  Side  claim  to  the  railroad.  Tt  is  proposed 
to  build  a  calcining  plant  at  San  Bernardino  to  treat  the  material. 

Judging  from  the  extent  of  the  croppings,  the  apparent  uniformity 
of  the  magnesite.  and  its  accessibility  to  a  railroad,  the  deposit  should 
become  an  important  producer. 

Bibliography.  Report  XYII.  pp.  353^-354. 

Qual^er  Group.  Geo.  W.  Elder,  799  Oak  St..  San  Francisco,  reports 
having  filed  relocations  (1923)  on  a  group  of  4  claims  covering  a 
deposit  of  magnesite' 12  miles  southeast  of  Cima,  in  the  Providence 
]^Iountains.  It  is  stated  that  a  shipment  of  200  tons  was  made  from 
this  deposit  to  a  plant  at  San  Diego,  before  the  Avar.  The  magnesite 
is  on  the  contact  between  serpentine  (footwall)  and  limestone 
(hanging  wall). 


76 


CALIFORNIA    STATE    MINING   BUREAU. 


SAN  DIEGO  COUNTY. 

No  magnesite  deposits  have  as  yet  l)een  found  in  San  Diego  County 
but  there  was  a  calcining  plant  in  operation  a  few  miles  south  of  the 
city  of  San  Diego  for  several  years,  treating  magnesite  that  is  mined 
at  Santa  IMargarita  Island  off  the  coast  of  Lower  California. 

International  Magnesite  Company.  Dr.  R.  Schiffman,  president, 
home  office,  Chamber  of  Commerce  Bldg.,  Pasadena,  Cal.  This  plant 
is  situated  at  Chula  Vista,  seven  miles  south  of  San  Diego.  It  has  a 
daily  capacity  of  forty  tons,  the  flow-sheet  being  as  follows :  The 
coarse  magnesite  was  broken  down  to  about  1"  size  by  a  No.  -S  gyra- 
tory crusher,  and  then  transported  by  a  belt  conveyor  to  two  sets  of 
rolls  where  it  was  still  further  reduced.  It  was  then  fed  directly  to  a 
5'  X  40'  oil-burning  rotary  ealciner.  From  the  calciner  the  product 
was  elevated  to  a  40'  cooling  tower.  It  was  then  about  ^"  size,  and 
running  dO'/o  MgO.  Most  of  the  calcined  magnesite  was  shipped  in 
bulk  Avithout  grinding,  to  steel  manufacturers  in  the  east ;  about 
10^   of  the  output  ])eing  used  for  plastic  purposes.     For  this  use  it 


Photo  No.  32 — I'laiii  ui  inieruaiiuHitl  Magii'-siU    C<jnipciuy    iiiuw  ijuraliio  Com- 
pany), at  Chula  Vista,  San  Dieg-o  County.     Photo  by  C.  A.  Waring. 

was  pulverized  in  buhr  mills  to  200  mesh,  and  then  packed  in  paper- 
lined  wood  barrels. 

The  company  formerly  treated  some  magnesite  from  Porterville, 
Tulare  Co.,    and  Bissell,  Kern  Co.,  but  later  only  IMexican  ore. 

After  being  idle  several  years,  this  plant  has  recently  been  liought 
by  the  Duralite  Company,  and  is  being  utilized  for  the  preparation 
of  stucco.    For  this,  they  buy  magnesite  already  calcined. 


SAN  LUIS  OBISPO  COUNTY. 

Magnesite  in  small  veins  has  been  reported  on  the  Kisar  place, 
eight  or  nine  miles  northwest  of  Cambria.  The  country  is  exceed- 
ingly rough  and  the  deposit  is  situated  a  long  way  from  railroad 
transportation.    The  port  of  San  Simeon  is  the  nearest  shipping  point. 

BiUiographu :  U.  S.  Geol.  Surv.,  Bull.  355,  p.  38. 


MAGNESITE   IN    CALIFORNIA.  77 

SANTA  BARBARA  COUNTY. 

Happy  Canon  Magnesia  Claims.  The  claims  are  situated  in  Sec. 
15,  T.  7  N.,  E.  29  AY.,  S.  B.  I\I.,  about  twelve  miles  southeast  of  Los 
Olivos,  near  the  base  of  the  San  Rafael  Alountiiins.  A  wagon  road 
from  Los  Olivos  runs  Avithin  two  miles  of  the  property.  A  few 
small  kidney-like  bunches  of  inagnesite  float  were  found  near  the 
head  of  Happy  Caiion,  but  none  has  been  found  in  place.  The 
country  rock  is  serpentine  which  iu  places  is  much  decomposed.  It 
extends  in  a  belt  iiorthwestAvard  for  several  miles  along  the  west 
slopes  of  the  San  Rafael  Mountains.  At  one  locality  above  Happy 
Creek  there  has  been  a  slide  in  the  serpentine  in  which  are  exposed, 
over  a  width  of  thirty  feet,  numerous  small  stringers  and  nodules 
of  magnesite.  This  latter  material  is  soft  and  somewhat  mixed 
up  with  the  soil,  Avhicli  gives  it  a  dirty-white  appearance.  This 
exposure  was  thought  by  the  locators  to  be  the  outcrop  of  a  magne- 
site ledge.  No  work  has  been  done  on  the  claims.  J.  M.  jMoraga  and 
C.  E.  Ruiz  of  Santa  Barbai-a,  are  the  owners. 


78  CALIFORNIA    STATE    MINING    BUREAU. 

SANTA  CLARA  COUNTY. 

Magne.site  deposits  occur  in  the  serpentine  areas  in  the  eastern 
portion  of  the  county,  the  largest  and  best  grade  deposits  thus  far 
uncovered  being  those  at  Red  Mountain  in  the  northeastern  corner 
of  the  county.  These  deposits  have  long  been  known  and  many 
attempts  made  to  develop  them,  but  their  distance  from  the  railroad, 
and  the  uncertainty  of  a  market,  long  delayed  their  exploitation ; 
and  it  is  only  within  the  last  decade  that  they  have  been  put  upon 
a  commercially  producing  basis. 

A  number  of  magnesite  croppings  occur  at  irregular  intervals  in  a 
belt  of  soft  impure  serpentine  along  a  low  range  of  hills  bordering 
the  east  side  of  the  Santa  Clara  Valley,  extending  from  east  of 
Coyote  Station  to  Gilroy.  These  croppings  are  small,  and  the  magne- 
site is  less  pure  than  the  Red  Mountain  deposits,  being  mixed  to 
some  extent  into  the  serpentine,  and  varying  in  color  from  white 
to  butf.  Several  of  these  deposits  have  been  developed,  and  during 
1916-1918,  considerable  crude  magnesite  was  shipped  out.  They 
have  the  advantage  of  being  within  easy  access  of  the  railroad. 

Bradford  Ranch  Deposit.  Magnesite  occurs  in  small  veins  in  ser- 
pentine four  miles  southeast  of  Edenvale,  along  the  top  of  an  open 
rolling  ridge.  In  addition  to  some  production  earlier,  this  Avas  wo7-ked 
to  some  extent  during  1917,  by  Harry  JMcLaughlin  of  San  Jose, 
who  shipped  out  several  car  loads. 

A  dump  on  the  hillside  above  the  Bradford  ranch  house  marks  the 
location  of  the  most  extensive  underground  work,  now  caved.  The 
country  rock  is  light-brown  serpentine  with  many  films  of  magnesite. 
Besides  this  caved  entry,  there  is  an  open  cut  now  partly  caved. 
Above  it  a  125-ft.  tunnel  driven  S.  30°  W.  found  no  ore.  Over  this 
is  a  tunnel  with  a  cross  drift  or  double  entry  which  followed  a  vein 
from  2"  to  10"  thick,  and  it  probably  produced  a  few  tons  of  ore, 
but  there  is  none  in  sight  now.  On  the  east  side  of  the  hill  near 
the  top,  a  cut  and  tunnel  80  feet  long  found  no  ore,  although  there 
is  a  suggestion  at  this  face  that  it  may  be  approaching  a  deposit. 
On  the  southeast  side  of  this  hill,  at  about  the  same  elevation  as 
other  developments,  there  is  a  cut  40  feet  long  which  leads  into  a 
curving  tunnel  following  a  nearly  vertical  vein  of  magnesite  which 
apparently  varies  from  a  few  inches  to  two  feet  thick.  The  footwall 
is  a  slip  fault,  and  the  hanging  wall  has  many  magnesite  veinlets  or 
fractures  in  brownish  serpentine.  Crosscuts  from  the  tunnel  dis- 
closed no  ore,  and  a  winze  in  the  floor  reaches  the  bottom  of  the  lens 
at  a  depth  of  eight  feet.  There  is  practically  no  ore  in  sight  in  the 
tunnel,  but  a  trench  just  above  shows  what  appears  to  be  the  top 
of  a  five-foot  vein.    A  few  tons  of  second  grade  ore  are  on  the  dump. 

Any  further  production  means  considerable  dead  work  to  under- 
cut the  veins  in  these  workings.  Herbert  S.  Bradford  of  San  Jose, 
is  the  owner. 

Bihliography :  Report  XVII,  p.  187. 

Burnett  Ranch  Deposit.  A  deposit  of  magnesite  was  developed 
on  this  ranch,  now  owned  by  Michael  Righetti,  several  years  ago. 
Veins  and  boulders  of  good  quality  occur  in  an  impure  serpentine 
near  the  'top  of  a  ridge  one-quarter  mile  north  of  the  Metcalf  road. 


MAGNESITE   IN    CAIJFORNIA.  79 

and  three  miles  northeast  of  Coyote  station.  A  vein  which  varied 
from  4'  to  10'  wide  was  mined  by  an  open  cut  1(X)'  long.  A  tunnel 
was  driven  on  this  vein  10'  below  the  floor  of  the  cut,  but  it  is  now 
caved.  About  75'  nortlnvest  of  this  working,  a  10-foot  tunnel  shows 
a  lens  of  white  magnesite  several  feet  in  diameter  and  up  to  one 
foot  thick.  There  are  about  ten  tons  on  the  dump.  A  small  cut 
300'  to  the  northwest  found  a  little  impure  magnesite,  and  700' 
northwest  of  the  original  location  a  cut  on  a  vein  striking  N.  45° 
W.  and  dipping  45°  SW..  took  out  a  lens  60'  long.  These  are  now 
caved  and  the  deposit  appears  to  l)e  worked  out.  Walter  Arnstein 
has  a  lease  on  the  mineral  rights  here,  but  the  property  is  idle. 

Bibliography:  Report   XA^II,    p.    187.     U.    S.    Geol.    Surv.,   Bull 
355.  p.  31. 

Cochrane  Ranch  Deposit  (also  known  as  the  Jackson  Ranch 
deposit)  is  4|  miles  east  of  !Madrone  Station,  and  1^  miles  south  of 
the  junction  of  Coyote  and  San  Felipe  creeks.  It  is  reported  that 
some  work  was  done  on  the  deposit  in  1897,  and  that  several  car- 
loads of  magnesite  were  shipped.  During  1916,  Harry  C.  Warwick. 
Hearst  Bldg.,  San  Francisco,  worked  it.  taking  out  several  hundred 
tons.  The  rock,  mainly  an  impure,  buff-colored  magnesite,  outcrops 
near  the  top  of  the  ridge  west  of  Coyote  Creek.  The  serpentine  is 
decomposed,  and  numerous  boulders  of  magnesite  have  been  taken  in 
the  opencuts.  There  is  no  well-defined  ledge  and  the  magnesite 
appears  to  be  deposited  as  large  blocks  or  boulders.  It  is  said  to 
contain  4%  iron,  to  which  it  owes  its  buflf  color,  though  in  part  some 
high-grade  Avhite  ore  has  been  shipped.  Xo  estimate  of  tonnage 
can  be  made,  as  the  banks  of  the  open  cuts  are  at  present  caved. 
In  1917  two  men  were  working,  using  hand  drills,  picks  and  shovels. 
The  ore  was  hauled  down  the  steep  hillside  to  the  floor  of  the  canon 
in  a  sled,  then  shoveled  into  wagons  and  hauled  by  four-horse  teams 
to  Madrone.  Alfred  Jackson,  Jr.,  operated  under  lease  for  a  time. 
There  was  a  small  tonnage  shipped  from  this  property  in  1922.  Mrs. 
A.  F.  Cochrane,  owner. 

The  Hoff  Ma^esite  Company,  Inc.,  (also  knoAvn  as  Black  Bird 
Valley  Mine;  owns  a  group  of  claims  on  Sec.  13,  T.  6  S.,  R.  4  E.. 
M.  D.  ]\I.,  on  which  a  vertical  kiln  was  built.  This  property,  together 
with  ground  leased  from  the  Winship  and  the  Stock  holdings  north 
of  the  Western  ^Magnesite  Develoi)ment  Company,  Avas  leased  by  Iloft* 
to  the  Standard  Magnesite  Company  in  1918.  John  D.  Hoft',"  j)resi- 
dent,  333  Monadnoek  Bldg.,  San  Francisco. 

Bibliography:  Cal.  State  Min.  Bur.,  Reports  XIII,  p.  505;  XVII 
p.  188;  Bull.  38,  p.  331.     U.  S.  Geol.  Surv.,  Bull.  355,  p.  31.       ' 

Jackson  Mine  (see  Cochrane  Ranch). 

Maltby  No.  1  Mine  (see  AVestern  Magnesite  Development  Co.). 

O'Connell  Bros.  Ranch  (formerly  Weber  Ranch).  Formerly  owned 
by  the  Bay  Cities  Water  Company.  Coyote,  California,  now  by  O'Con- 
nell Bras.  This  ranch,  which  extends  over  an  area  of  several  square 
miles,  contains  two  groups  of  magnesile  deposits,  which  we  will 
designate  "the  'north'  and  'south'  groups,  respectively. 


80  CALIFORNIA    STATE    MINING   BUREAU. 

The  north  group  is  h^cated  on  an  open  ridge,  about  three  miles 
in  an  air  line  northeast  of  Madrone.  A  tew  car  loads  were  shipped 
by  II.  Sherlock  during  1915  to  Berkeley  for  the  manufacture  of 
carbon  dioxide,  and  during  1916  some  further  development  woi-k 
was  done  by  the  AVater  Company  under  the  mnnagement  of  II.  L. 
Haehl  of  San  Francisco,  but  the  deposits  found  were  too  small  to 
warrant  exploitation,  and  work  ceased.  On  the  west  slope  of  the  hills 
near  the  top,  a  deposit  was  later  developed  under  lease  by  H.  C. 
Warwick  of  San  Francisco,  followed  by  a  Mr.  Madison.  A  large 
open  cut  shows  a  ledge  of  white  to  butf-colored  magnesite.  Several 
hundred  tons  have  been  produced  from  this  deposit.  An  aerial 
tram  conveyed  the  ore  to  a  bunker  at  the  foot  of  the  hill,  whence 
it  was  hauled  by  truck  to  the  railroad  at  Madrone. 

On  the  east  slope  considerable  float  has  been  found  and  several 
large  cuts  were  made  in  the  hope  of  striking  the  ore  in  place.  The 
magnesite  occurs  here  in  bunch-like  or  kidney  deposits,  being  evi- 
dently not  deposited  in  a  vein  or  lode,  but  as  a  general  alteration  of 
the  serpentine  with  which  it  is  closely  associated.  The  slopes  of  the 
ridge  are  covered  with  an  adobe  soil,  and  the  serpentine  very  much 
decomposed,  but  the  development  work  indicates  these  deposits  are 
in  place.    The  kidneys  or  boulders  are  white  and  evidently  quite  pure. 

The  property  has  been  idle  since  1919,  and  when  visited  by  the 
writer  in  November,  1923,  a  part  of  the  tramway  cable  had  been 
taken  down  and  removed.  The  formations  uncovered  in  the  several 
openings  indicate  that  the  magnesite  occurs  in  small  irregular  veins, 
in  part  reticulated,  and  some  irregular  masses.  In  the  upper  work- 
ings near  the  top  of  the  ridge,  the  magnesite  is  more  massive,  but 
also  irregular. 

The  magnesite  in  the  south  group  of  deposits  on  the  O'Connell 
ranch  is  distinctly  different  in  character  from  that  in  the  north 
group  described  above.  It  outcrops  in  large,  rugged  masses  for  at 
least  a  mile  along  the  eastern  side  of  a  ridge  which  trends  northward 
between  Coyote  Creek  and  the  main  Santa  Clara  Valley  east  of 
Madrone.  It  if  3^  miles  by  road  from  Madrone.  On  a  recent  inspec- 
tion of  this  property  by  the  writer  (August,  1925),  these  croppings 
were  noted  through  a  vertical  distance  of  at  least  500  feet  from  the 
creek  level  to  near  the  top  of  the  ridge,  Some  nodular,  high-grade, 
white  ore  was  observed,  but  the  material  is  mostly  brown,  massive, 
and  siliceous.    Analyses  are  stated  to  show  up  to  5%  FeoO-.. 

AV.  H.  Cone,  of  San  Francisco,  and  associates  have  a  lease  on  both 
groups  of  deposits  and  are  organizing  a  company  to  operate.  The 
brown,  siliceous  material  in  the  south  group  will  be  utilized  for  the 
manufacture  of  metallic  magnesium  by  a  new,  patented  process 
stated  to  have  been  developed  recently  in  Germany  on  a  commercial 
basis.    A  calcining  plant  will  l)e  liuilt  on  the  railroad  at  IMadrone. 

BiUiography:  Cal.  State  Min.  Bur.,  Report  XVII,  p.  189;  Bull. 
38,  p.  331.     IT.  S.  Geol.  Surv.,  Bull.  355,  p.  32. 

The  Pacific  Magnesite  Company  of  San  Francisco  operated  for  a 
short  time  on  ten  claims  on  Red  Mountain  adjoining  the  property 
of  the  AVestern  Magnesite  Development  Company  on  the  south,  33 


MAQNESITE   IN    CALIFORNIA.  81 

miles  southeast  of  Liverniore.  The  claims  were  located  in  1915, 
and  some  development  work  done  the  following  year.  In  1917,  the 
property  was  tied  up  due  to  litigation  over  the  ownership,  following 
which,  ijy  order  of  the  court,  is  reverted  to  the  Western  ]\Iagnesite 
Company. 

Two  tunnels  were  driven  at  elevations  of  about  50  and  lUO  feet 
below  a  large  cropping  of  magnesite  near  the  top  of  the  ridge.  The 
lower  tunnel  400  feet  long,  cuts  the  ledge  exposing  an  orebody  of 
almost  pure-white  magnesite.  A  gravity  tramway  1200  feet  long, 
with  a  drop  of  -400  feet,  connects  the  loAver  tunnel  with  an  ore  bin 
above  the  road.  A  65  h.  p.  gas  engine  and  Giant  air  compressor 
Avere  installed  to  supply  the  necessary  air  for  the  machine  drills. 
A  small  kiln  Avas  later  built  for  calcining  the  ore,  and  preparations 
made  to  mine  a  large  tonnage  daily.  The  freight  rate  in  1917  to 
Livermore,  the  shipping  point,  was  $5  per  ton.  The  company 
was  considering  the  construction  of  a  4-mile  wagon  road  to  the 
terminus  of  the  Patterson  and  AVestern  Railroad,  on  the  east  side 
of  the  range,  which  would  have  materially  lessened  the  high  trans- 
portation cost.  That  railroad,  however,  has  since  gone  out  of 
existence. 

The  Hoff-Price  Company,  Alonadnoek  Bldg.,  San  Francisco,  had 
a  lease  on  several  claims  of  the  Pacific  ]\Iagnesite  Company,  from 
which  they  shipped  a  few  ear  loads  of  magnesite  in  the  spring  of 
1917.  Work  ceased  here  when  that  company  began  operations  at 
the  Sampson  magnesite  mine  in  San  Benito  Count5^ 

Bibliography :  Report  XVII,  p.  188. 

The  Standard  Magnesite  Company,  for  several  months  during  the 
first  part  of  1918,  operated  a  maunesite  property  in  the  Red  Aloun- 
tain  district,  about  33  miles  southeast  of  Livermore,  in  Sec.  18,  T.  6 
S.,  R.  5  E.,  but  operations  were  discontinued  in  September  of  the 
same  year.  The  company  leased  several  claims,  only  one  of  which 
has  been  developed.  The  claims  are  owned  by  Airs.  H.  E.  Stock, 
Venice,  Cal.  There  are  two  tunnels,  one  of  which  is  200  feet  long, 
and  the  other  about  75  feet.  Considerable  ore  was  hauled  to  Liver- 
more, and  shipped,  calcined.  An  average  of  12  men  were  employed; 
there  was  considerable  equipment  at  the  property  consisting  of  a 
vertical  kiln,  an  air  compressor,  drills,  track,  cars,  etc. 

Bibliography :  Report  XVII,  p.  188. 

Western  Magnesite  Development  Company,  Chas.  H.  Spinks,  presi- 
dent. Palm  Ave.  and  Lee  St.,  Los  Altos.  (Known  also  as  Maltby 
Xo.  1  mine).  The  property  during  1917  and  1918  was  operated 
under  Langdon  E.  Boyle,  as  receiver,  appointed  by  the  Federal  Court, 
on  account  of  litigation  betw(>en  confiicting  factions  in  the  company. 
The  company,  organized  in  1912,  owns  the  magnesite  mine  on  Red 
Mountain  formerly  owned  by  the  American  Magnesite  Company. 
The  property  consists  of  ten  claims,  four  of  which  are  patented,  and 
has  been  a  producer  since  1905.  The  magnesite  outcrops  in  bold 
white  ledges  on  the  southern  and  western  slopes  of  the  mountain, 
several  hundred  feet  above  the  floor  of  the  valley.     The  following 

6—39802 


82 


CAIJFORNIA    STATE    MINING    BUREATT. 


•  3  C     c 

in 

2^  i 


ri.ATE   VIII 


MAGNESITE    IN    CAIJFORNIA. 


83 


tlesei'iptioii  of  the  i^-eolo^^v   is  (iiiotcd  from  the  report  of  (Jale,'    wlio 
made  an  examination  of  the  deposits  in  September.  1!)12: 

"The  general  area  containing  the  masnesite  outcrops  is  occupied  by  serpentine 
without  evidence  of  much  variation  in  character  or  of  incluslveness  of  other  rocks. 
The  serpentine  is  bordered  on  the  west  by  sedimentary  sandstones  and  shales  which 
form  a  distinctlv  different  topography.  Tlie  otlier  limits  of  the  mass  of  serpentine 
rock  have  not  been  defined.  The  original  country  rock  from  which  the  serpentine 
is  derived  is  described  by  Hess=  as  Iherzolite  and  peridotite,  and  is  composed 
essentially  of  the  minerals  olivene,  diopside,  and  an  orthorhombic  pyroxene.  The 
mineral  serpentine  is  a  natural  alteration  product  from  such  rocks.  The  original 
country  rocks  are  composed  princii^ally  of  silicates  of  magnesia  (silica  40  +  %: 
m;ignesia  25  to  i0'7'(  ;  alumina  and  iron  variable,  usually  59f  or  more;  and  a  small 
percentage  of  alkalies).  It  is  natural  to  assume  the  magnesite  might  be  derived 
by  tlie  decomposition  or  alteration  of  these  silicates  being  deposited  as  veins 
along  fissure  zones,  or  by  replacing  tlie  country  rock.  As  a  whole,  however,  the 
serpentine  of  this  area  does  not  show  the  excessive  amount  of  shearing  to  be 
seen   at  any  of  tlie  otlier  magnesite  localities. 

"Throughout  the  dark-red  soil  that  covers  the  area  of  serpentine  country  rock, 
especially  in  the  zone  that  contains  the  magnesite  veins,   silica  is  present   in  various 


'luiTo  Nil.  :i:! — ( ip.'u  lilt  of  Wcst»Tii  Magnesite  Development  Company  (in  1915). 
Note  lack  of  outcrop  of  this  large  lx)dy  of  magnesite.  Ground  surface  sliowing 
in  upper  right  half  of  picture. 


forms.  It  occurs,  in  part,  as  a  white  rosiny  opal,  scattered  fragments  of  which 
are  strewn  about  on  the  surface,  or  it  may  be  observed  as  chalcedonic  veins  or 
coatings  in  the  joints  of  the  country  rocks.  The  silica  associated  with  the  purer 
mass  of  magnesite  in  the  larger  pit  was  in  the  form  of  a  pale-greenish  granular 
iiuartz. 

"The  magnesite  veins  are  very  irregularly  distributed  and  appear  to  trend  in 
all  directions.  The  larger  developed  masses  are  of  most  unusual  size,  and  even 
the  great  bodies  that  have  been  removed  by'  mining  have  been  taken  out  in  large 
"l)en  caves  or  chambers,  so  as  to  give  little  evidence  of  the  real  extent  or  size  of 
tlie  deposits  underground,  beyond  that  which  has  been  taken  out." 

'Gale  H.  S.,  Magnesite  deposits  in  California  and  Nevada:  U.  S.  Geol.  Surv., 
Bull.    540,   pp.    4;iS-501,    1914. 

=  Hess,  P.  L.,  Magnesite  deposits  of  California:  U.  S.  Geol.  Surv.,  Bull.  355, 
p.   34.  1908. 


MAGNESITE    IN    CAI.IFORNIA. 


83 


(U'serii)tion  of  tlie  j,H'ol()fi:y   is  ((uolcd  fi-oin  the  report  of  dale,'   who 
iiuule  an  examination  of  the  (U'posits  in  Septenil)er.  11)12: 

"The  general  area  containing  the  masnesite  outcrops  is  occupied  by  serpentine 
without  evidence  of  much  variation  in  character  or  of  inclusiveness  of  other  rocks. 
Tlie  serpentine  is  bordered  on  tlie  west  by  sedimentary  sandstones  and  shales  which 
form  a  distinctly  different  tojiography.  The  other  limits  of  the  mass  of  serpentme 
rock  have  not  been  defined.  Tlie  original  country  rock  from  which  tlie  serpentine 
is  derived  is  described  by  Hess=  as  Iherzolite  and  peridotite,  and  is  composed 
essentially  of  the  minerals  olivene,  diopside,  and  an  orthorhombic  pyroxene.  The 
mineral  serpentine  is  a  natural  alteration  product  from  such  rocks.  Tlie  original 
country  rocks  are  composed  principally  of  silicates  of  magnesia  (silica  40  +  %; 
magnesia  25  to  40'X  ;  alumina  and  iron  variable,  usually  5%  or  more;  and  a  small 
percentage  of  alkalies).  It  is  natural  to  assume  the  magnesite  might  be  derived 
by  the  decomposition  or  alteration  of  these  silicates  being  deposited  as  veins 
along  fissure  zones,  or  by  replacing  the  country  rock.  As  a  whole,  however,  the 
serpentine  of  this  area  does  not  show  the  excessive  amount  of  shearing  to  be 
seen  at  any  of  the  otlier  magnesite  localities. 

"Throughout  the  dark-red  soil  that  covers  the  area  of  serpentine  country  rock, 
especially   in   the  zone  that  contains   the  magnesite   veins,    silica    is  present   in  various 


HoTo  No.  .'!:! — Open  cut  of  Western  Magnesite  Development  Company  (in  1915). 
Note  lack  of  outcrop  of  this  large  Ixidy  of  magnesite.  Ground  surface  sliowing 
in  upper  right  half  of  picture. 


forms.  It  occurs,  in  part,  as  a  white  rosiny  opal,  scattered  fragments  of  which 
are  strewn  about  on  the  surface,  or  it  may  be  observed  as  chalcedonic  veins  or 
coatings  in  the  joints  of  the  country  rocks.  The  silica  associated  with  the  purer 
mass  of  magnesite  in  the  larger  pit  was  in  the  form  of  a  pale-greenish  granular 
quartz. 

"The  magnesite  veins  are  very  irregularly  distributed  and  appear  to  trend  in 
all  directions.  The  larger  ileveloped  masses  are  of  most  unusual  size,  and  even 
the  great  bodies  that  liave  been  removed  by'  mining  have  been  taken  out  in  large 
open  caves  or  chambers,  so  as  to  give  little  evidence  of  the  real  extent  or  size  of 
the  deposits  underground,  beyond  that  which  has  been  taken  out." 


'  Gale  H.  S.,  Magnesite  deposits  in  California  and  Nevada :  U.  S.  Geol.  Surv., 
Bull.    540,   pp.    49  8-501,    1914. 

=  Hess,  F.  L.,  Magnesite  deposits  of  California :  U.  S.  Geol.  Surv.,  Bull.  355, 
p.   ."54,  1908. 


84 


CALIFORNIA    STATE    MINING   BUREAU. 


Plate  IX, 


WHITE    DIAMOND    WORKINGS 

MALTBY  MAGNESITE    MINES    N?  I 

LIVERMORE.    CALIFORNIA 


o  5  oo-r-es^  of  c  ! 


MAGNESITE   IN    CALIFORNIA.  85 

The  properties  of  the  Western  IMagnesite  Development  Company 
are  located  mainly  in  T.  6  S.,  R.  5  E.,  M.  D.  M.,  along  the  summit 
of  Red  ]\Ionntain  ridge  which  forms  the  boundary  line  between 
Santa  Clara  County  and  Stanislaus  County,  to  the  east.  This  group 
has  been  operated  under  lease  by  C.  S.  ]\laltby,  Humboldt  Bank  Bldg., 
San  Francisco,  since  1919.  Many  improvements  have  been  made 
in  the  plant  equipment,  and  new  orebodies  have  been  developed.  The 
earlier  underground  operations  were  due  east  from  the  furnaces,  and 
some  ore  is  still  ])eing  drawn  from  that  portion  of  the  property. 
Ivater  developments  have  been  towards  the  north  and  northwest  from 
the  older  Avorkings.  While  none  of  the  north-end  stopes  have  as 
yet  reached  the  size  of  some  of  the  older  south-end  orebodies  (there 
was  one.  ;^00'  long  x  50'  wide  x  300'  high  ;  and  another  200'  long  x 
150'  high  X  30'  wide),  some  are  over  20'  wide  in  places.  The  ore  is 
of  the  same,  white,  high-grade  character. 

The  accompanying  maps  of  the  claims  and  the  mine  workings  are 
are  here  reproduced  through  the  courtesy  oi;  Mr.  Maltby  and  his 
mine  superintendent,  Mr.  Roy  II.  Clarke.  The  magnesite  is  in  gen- 
eral high  grade,  though  towards  the  border  of  the  larger  bodies  it 
becomes  mixed  with  the  soft  serpentine  country  rock,  having  a 
yellowish  color,  so  that  there  is  no  well-defined  boundary. 

Ore  from  the  north  end  is  trammed  around  the  hill  (see  photo) 
to  the  loading  bunkers  of  the  main  aerial  tram  (of  which  there  were 
two).  The  larger  and  heavier  of  the  tv*'o  tramways  to  the  main 
south  workings  is  3000  feet  long  Avith  a  drop  of  550  feet  from  ore 
bins  to  furnaces.  When  visited  in  November,  1923,  preparations 
were  being  made  for  the  installation  of  a  third  aerial  tramway,  at 
the  north  end,  in  order  to  eliminate  the  long  haul  around  the  hill. 
A  total  of  150-200  tons  of  ore  per  day  was  being  delivered  to  the 
furnaces,  of  Avhich  40  tons  was  being  mined  at  the  south  end,  30  tons 
from  the  extreme  north  end,  and  the  balance  from  the  main  north 
workings.  A  new  4-inch  pipe  line  was  being  laid  direct  to  the  north 
end  to  serve  those  workings  with  compressed  air,  in  place  of  the 
line  from  the  south  end  around  the  hill.  Pressure  is  maintained  at 
TOO  pounds  at  the  compressors  (two  50  h.  p.  Chicago  Pneumatic, 
direct-connected  to  oil  engines;  also  a  Doak  compressor  as  extra 
stand-by)  and  at  least  90  pounds  at  the  mine. 

There  are  four  upright  kilns  which  l)urn  the  lump  ore,  and  a  Scott 
fine-ore  fjuicksilver  furnace  which  handles  the  fines. ^  The  burners 
nsed  on  the  upright  kilns  have  2,  3  and  4  tips,  in  order  to  spread  the 
Hame;  I>ut,  single-tip  burners  are  used  in  the  Scott  furnace.  The 
ore  as  it  comes  from  the  mine  is  dumped  on  grizzlies  set  with  a 
l;',-inch  oi)ening;  and  the  through  material  passed  over  a  ^-inch 
screen.  The  plus  i[-inch  material  goes  to  the  Scott,  and  the  minus 
^-inch  to  the  waste  dump  as  it  contains  mostly  impurities.  There 
is  a  Thwing  electric  pyrometer  on  the  Scott  furnace,  by  which  the 
temperature  is  maintained  at  2100°  F.  The  calcines  are  drawn  each 
hour,  and  an  output  of  20-24  tons  per  day  obtained.  The  upright 
k'ilns  are  drawn  every  2  hours,  and  their  output  totals  50  tons  daily 
for  the  four.     The  ])urned  lump  ore  is  carried  by  a  belt  conveyor  to 

•  Since  the  above  was  written,  we  are  informed  that  a  rotary  kiln  has  been  added 
for  calcining  the  fines. 


MAGNESITE   IN    CALIFORNIA.  85 

The  properties  of  the  Western  Magnesite  Development  Company 
are  located  mainly  in  T.  6  S.,  R.  5  E.,  M.  D.  M.,  alonp:  the  summit 
of  Red  ]\Ionntain  ridge  which  forms  the  boundary  line  between 
Santa  Clara  County  and  Stanislaus  County,  to  the  east.  This  group 
has  been  operated  under  lease  by  C.  S.  IMaltby,  Humboldt  Bank  Bldg., 
San  Francisco,  since  1019.  Many  improvements  have  been  made 
in  the  plant  equi])ment,  and  new  orebodies  have  been  developed.  The 
eaj'lier  undergi-oiind  operations  were  due  east  from  the  furnaces,  and 
some  ore  is  still  being  drawn  from  that  portion  of  the  property. 
Later  developments  have  been  towards  the  north  and  northwest  from 
the  older  workings.  While  none  of  the  north-end  stopes  have  as 
yet  reached  the  size  of  some  of  the  older  south-end  orebodies  (there 
was  one,  300'  long  x  50'  wide  x  300'  high ;  and  another  200'  long  x 
150'  high  X  30'  wide),  some  are  over  20'  wide  in  places.  The  ore  is 
of  the  same,  white,  high-grade  character. 

The  accompanying  maps  of  the  claims  and  the  mine  workings  are 
ai-e  hei-e  reproduced  through  the  courtesy  of  ]Mr.  Maltby  and  his 
mine  superintendent,  Mr.  Roy  II.  Clarke.  The  magnesite  is  in  gen- 
ct-al  high  grade,  though  towards  the  border  of  the  larger  bodies  it 
becomes  mixed  with  the  soft  serpentine  country  rock,  having  a 
yellowish  color,  so  that  there  is  no  well-defined  boundary. 

Ore  from  the  north  end  is  trammed  around  the  hill  (see  photo) 
to  the  loading  bunkers  of  the  main  aerial  tram  (of  which  there  were 
two).  The  larger  and  heavier  of  the  two  tramways  to  the  main 
south  workings  is  8000  feet  long  with  a  drop  of  550  feet  from  ore 
bins  to  furnaces.  When  visited  in  November,  1923.  preparations 
were  being  made  for  the  installation  of  a  third  aerial  tramway,  at 
the  north  end,  in  order  to  eliminate  the  long  haul  around  the  hill. 
A  total  of  150-200  tons  of  ore  per  day  was  being  delivered  to  the 
furnaces,  of  which  40  tons  was  being  mined  at  the  south  end,  30  tons 
from  the  extreme  north  end,  and  the  balance  from  the  main  north 
Avorkings.  A  new  4-inch  pipe  line  was  being  laid  direct  to  the  north 
end  to  serve  those  Avorkings  with  compressed  air,  in  place  of  the 
line  from  the  south  end  around  the  hill.  Pressure  is  maintained  at 
100  pounds  at  the  compressors  (two  50  h.  p.  Chicago  Pneumatic, 
direct-connected  to  oil  engines;  also  a  Doak  compressor  as  extra 
stand-by)  and  at  least  90  pounds  at  the  mine. 

There  are  four  upright  kilns  which  burn  the  lump  ore,  and  a  Scott 
fine-ore  quicksilver  furnace  which  handles  the  fines.^  The  burners 
used  on  the  upright  kilns  have  2.  3  and  4  tips,  in  order  to  spread  the 
tiame;  but,  single-tip  burners  are  used  in  the  Scott  furnace.  The 
ore  as  it  comes  from  the  mine  is  dumped  on  grizzlies  set  with  a 
Ij-inch  opening;  and  the  through  material  passed  over  a  ff-inch 
screen.  The  plus  iJ-inch  material  goes  to  the  Scott,  and  the  minus 
^-inch  to  the  waste  dump  as  it  contains  mostly  impurities.  There 
is  a  Thwing  electric  pyroineter  on  the  Scott  furnace,  by  which  the 
temperature  is  maintained  at  2100°  F.  The  calcines  are  drawn  each 
hour,  and  an  output  of  20-24  tons  per  day  obtained.  The  upright 
kilns  ai-e  drawn  (!very  2  hours,  and  their  output  totals  50  tons  daily 
for  the  four.     The  Inii-ned  lump  ore  is  carried  by  a  belt  conveyor  to 

■  Since  the  above  was  written,  wo  are  informed  that  a  rotary  kiln  has  been  added 
for  calcining  the  fines. 


86 


CALIFORNIA    STATE    MINING   BUREAU. 


MAGNESITE    IN    CALIFORNIA. 


87 


a  troinnu4  with  1-inch  apertures.  The  waste  and  oflt'-eolored  matyne- 
site  are  picked  off  the  belt.  The  iinbiirned  cores  after  passing  out  of 
the  trommel  are  hauled  back  to  the  main  ore  bin  and  reburned  in 
the  kilns.  Steam  for  atomizing  the  fuel-oil  is  provided  by  two 
boilers,  of  100  h.  p.  and  65  h.  p.,  respectively.  There  were  14  motor 
trucks  in  service,  hauling  the  calcined  magnesite  to  the  railroad  at 
Tiivermore.    On  the  return  trip  they  bring  out  fuel-oil  in  drums. 

BihJio(jraphy:  Cal.  State  Min.  Bur.,  Reports  XI.  p.  374;  XII,  p. 
328';  XIII.  p.  505;  XVII,  pp.  189-192;  XX.  pp.  29-30;  Bull.  38, 
pp.  330-331.  U.  S.  Geol.  Surv.,  Bull.  355,  pp.  33-37 ;  Bull.  540, 
pp.  498-501.  Eng.  and  Min.  Jour.-Fress.  Vol.  120.  pp.  178-180, 
Aug.  1.  1925. 


Photo  No.  36 — Ti-amming  ore  from  north  end  of  White  Diamond  workings,  at  MaUby 
No.   1   Mine    (Western  Magnesite  Development  Co.)    on  Red  Mountain. 

Winship  Properties.  K.  1).  Winshii)  Estate.  350  Post  St..  Shu  Fran- 
cisco, owner.  Magnes^ite  occurs  on  Sees.  1  and  11,  T.  6  S.,  R.  4  E.,  and 
on  the  SW-j  of  Sec.  7,  T.  6  S.,  R.  5  E.,  M.  D.  ]M.  The  two  latter  were 
leased  to  the  John  D.  Hoif  Asbestos  Company  with  offices  at  333 
Monadnock  Bldg..  San  Francisco.  The  principal  development  work. 
so  far.  has  been  done  on  Sec.  11  from  which  several  carloads  of  crude 
magnesite  were  shipped  in  1916,  via  Livermore. 


88 


CALIFORNIA   STATE    MINING   BUREAU. 


^4. 


Photo  No.  37- — Vertical  kiln  of  the  Western  Magnesite  Development  Company. 


Photo  No.  ?,S — gcott.  fine-ore,  quieksilver  furnace  (at  right),  rebuilt  and  in  use 
for  calcining  magnesite  fines  at  Western  Magnesite  Development  Company 
(Maltby  No.  1)  property,  Santa  Clara  County.  Storage  bunkers  with  elevator 
for  calcined  fines  in  center.  Four  vertical-stack  kilns  at  left,  for  burning 
lump  ore.     Photo  by  C.   S.   Maltby. 


MAGNESITE   IN    CALIFORNIA.  89 

SONOMA  COUNTY. 

There  are  numerous  deposits  of  uiagnesite  in  Sonoma  County,  some 
of  which  are  in  the  district  around  Cloverdale,  and  another  group 
is  situated  northwest  of  Guerneville  in  a  belt  of  serpentine  which 
strikes  northwestward  through  T.  8  N.,  R.  10  W.,  and  T.  9  N.,  R. 
11  W..  ]\I.  D.  M.  The  latter  region  is  rather  inaccessible,  being 
characterized  by  densely  vvooded  and  brush-covered  ridges  separated 
by  narrow  eafions.  It  was  not  until  1913  that  attempts  were  made 
to  exploit  the  deposits.  The  more  important  of  these  are  controlled 
by  the  Sonoma  INIagnesite  Company  and  the  Western  Carbonic  Acid 
Gas  Company  (now  Harker  Estate),  the  former  having  shipped 
during  1915  and  1916.  several  thousand  tons  to  New  York  via  the 
Panama  Canal. 

The  magnesite  deposits  northwest  of  Guerneville  shoAV  some  of 
the  most  extensive  surface  exposures  in  the  state,  and  it  is  due 
mainly  to  their  inaeeessilnlity  that  they  are  idle.  The  roads  to  both 
Cazadero  and  Guerneville,  the  nearest  railroad  stations,  are  almost 
impossible  to  haul  over  due  to  the  heavy  grades.  The  construction 
of  a  2'1-inch  gauge  railroad  up  East  Austin  Creek  to  within  three 
miles  of  their  deposit,  by  the  Sonoma  Magnesite  Company,  did 
away  with  the  haul  to  Cazadero,  but  as  the  magnesite  has  to  be 
transshipped  to  the  narrow  gauge  at  Magnesite  station,  and  then 
in  turn  to  the  ])road  gauge  seven  miles  beyond  at  Duncan  Mills, 
the  freight  rate  by  this  route  is  high.  With  better  transportation 
facilities,  this  district  should  become  an  important  producer. 

Bihliographij:  Cal.  State  Min.  Bur.,  Reports  XIV,  pp.  324-333; 
XVil,  p.  249;  Bull.  38,  pp.  331-333.  U.  S.  Geol.  Surv.,  Bull. 
355,  pp.  22-28 ;  Bull.  540,  pp.  480-498. 

Albertz  Ranch  Deposits.  A  vein  of  magnesite  has  been  mined  on 
this  property  two  miles  southwest  of  Cloverdale,  by  a  trench  or 
cut  driven  along  it  for  80  feet.  The  inner  end  of  the  cut  is  about 
30  feet  deep,  and  shows  in  the  face  6"  to  1  ft.  of  chalky  white  magne- 
site. The  vein  which  dips  vertically  in  places,  is  3  feet  thick,  aver- 
aging about  2  feet.  Parts  of  it  are  full  of  serpentine  breccia.  One 
carload  has  been  shipped  and  there  were  about  40  tons'  in  stock, 
when  visited.  Fifty  feet  from  this  trench  is  the  top  of  another 
vein,  probably  15"  to  24"  thick,  undeveloped.  The  developed  vein 
pinches  out  and  has  not  been  traced  on  the  surface.  Pi'obably  a 
few  hundred  tons  may  be  developed  on  the  second  vein.  Ferdinand 
Albertz,  Cloverdale,  owner. 

Battenburg  Refractory  Magnesite  Mine  (formerly  known  as  the 
Creon  or  Rolling  deposit).  It  is  situated  in  See.  32]  T.  12  X.,  R.  10 
AV.,  M.  D.  M.,  three  miles  by  road  east  of  Preston  station,  near  the 
top  of  a  ridge  at  an  elevation  of  1500  feet.  The  wagon  road  to 
Preston  has  a  heavy  grade,  but  it  is  all  down  hill,  and  the  magne- 
site was  hauled  out  by  teams  at  $1.50  per  ton. 

The  deposit  occurs  in  the  form  of  disconnected  veins  oi'  narrow 
lenses  in  the  serpentine,  which  trend  north  and  south,  and  dip 
almost  vertically.  These  vai-y  in  thiekness  from  a  few  inches  to 
several  feet,  and  up  to  50  feet  in  length.  The  serpentine  is  so 
faulted  that  there  is  no  continuity  to  the  veins,  and  consequently 


90 


CALIFORNIA    STATE    MINING   BUREAU. 


their  extent  is  very  uncertain.  Development  work  consists  of  two 
tunnels,  the  lower  50  feet  vertically  below  the  upper.  Five  lenses 
have  thus  far  been  developed  in  the  upper  tunnel  which  is  over  300 
feet  long,  and  three  in  the  lower  which  is  over  400  feet  in  length. 
Several  of  the  lenses  or  orebodies  have  been  exhausted,  having  been 
stoped  between  the  two  levels.  A  few  small  croppings  north  of  the 
mine  were  being  developed  by  open  cuts,  when  operations  ceased. 
Quoting  from  Bess's  report:  ^ 

"The  magnesite  in  the  worked  deposit  is  but  little  discolored,  and  portions  are 
pure  white,  but  all  through  it  is  scattered  some  serpentine  only  partially  altered  to 
magnesite.  The  mass  has  been  much  crushed  and  the  pieces  have  been  recemented 
by  crystalline  magnesite  of  a  slightly  greenish-yellow  color,  which  forms  a  layer 
about  one  thirty-second  of  an  inch  thick  around  the  fragments.  In  places  colorless, 
fragile,  platy  crystals  coat  the  cavities." 


Photo  No.   39 — Kiln  of  the  Refractory  Magnesite  Mine,   east  of  Preston, 
Sonoma  County. 


The  dead-burned  product  from  this  mine  is  brown  in  color,  very 
much  resembling  the  Austrian  'spaeder,'  so  much  desired  as  a  refrac- 
tory. Analyses  show  an  average  of  around  6%  FeoO;^,  with  a  low 
silica  and  no  lime  content.  The  raw  material  appears  to  be  an 
isomorphous  mixture  of  the  carbonates  of  magnesium  and  ferrous 
iron,  the  pale-green  color  on  thin  fracture-edges  being  due  to  the 
iron.  The  entire  output  was  dead-burned  at  the  mine,  and  shipped 
to  a  fire-brick  manufacturing  plant  at  Stockton,  the  resulting  magne- 
sia bricks  being  utilized  by  metallurgical  plants  in  California  and 
Utah. 

The  magnesite  is  calcined  in  a  30-ton  capacity  stack  kiln,  using 
crude-oil  fuel.  A  20  h.  p.  gas  engine  and  compressor  supplied  the 
necessary  air  for  the  hammer  drills  used  in  the  mine.     An  average 

'Hess,  F.  L.,  Magnesite  deposits  of  California:  U.  S.  Geol.  Surv.,  Bull.  355,  pp. 
22-23,  1908. 


MAGNESITE    IN    CALIFORNIA.  91 

of  ten  men  were  employed,  the  production  being  four  to  five  tons 
of  calcined  rock  daily.  Tlie  mine,  opened  about  1907.  was  worked 
l)y  the  present  owner,  the  Refractory  ^Maunesite  Company,  F.  R. 
Turton,  president  (since  deceased),  from  1914  to  1921.  A  total  of 
several  thousand  tons  has  been  produced. 

Bibliography:  Cal.  State  Min.  Bur..  Reports  XIV,  pp.  325-826; 

XVII,  p.  249;  Bull.  38,  pp.  331-332.     U.  S.  Geol.  Surv.,  Bull. 

355,  pp.  22-24. 

Burgans  Ranch  Deposit.  Numerous  small  stringers  or  veinlets  of 
magnesite  occur  in  the  serpentine  on  this  ranch,  Avhich  is  about  a 
mile  north  of  the  Battenburg  mine,  and  on  the  same  ridge.  About 
250  feet  beloAv  the  summit  of  the  ridge,  an  open  cut  was  made  on 
several  veinlets.  It  is  in  probably  15  feet,  showing  a  stockwork  of 
veinlets  across  a  6-foot  face;  260  feet  below  the  cut  a  funnel  was  ■ 
driven  about  20  feet,  but  failed  to  disclose  any  vein.  Some  large 
lioulders  of  almost  pure-white  magnesite  are  found  on  the  ranch, 
but  no  deposit  of  any  commercial  importance  has  been  developed, 
("has.  H.  Burgans,  Cloverdale,  owner. 

Madeira  Deposit  (also  known  as  Healdsburg  Marble  Company). 
It  is  in  the  southwest  corner  of  Sec.  31,  T.  9  X.,  R.  10  W.,  M.  D.  M., 
5^  miles  north  from  Guerneville;  elevation  1700  feet,  (bar.).  There 
is  a  series  of  magnesite  veins  from  a  few  inches  to  ten  feet  wide, 
occurring  in  serpentine  over  a  width  of  about  1400  ft.  They  strike 
west  of  north  and  dip  west  at  about  70°.  The  larger  veins  are  of  very 
uood  (luality.  There  is  a  considerable  tonnage  in  sight  at  the  surface 
which  can  be  cheaply  quarried,  but  except  for  a  couple  of  short 
tunnels,  there  has  been  no  development  work  underground. 

At  its  west  end,  the  veins  are  narrow  and  banded  with  a  green 
dolomitic  material,  chalcedony  and  quartz,  forming  a  variety  of 
'verde  antique  marble.'  It  Avas  for  this  that  the  deposit  was  origin- 
ally located  (1894)  with  the  intention  of  putting  it  on  the  market  as 
an  ornamental  building  stone. 

The  property  is  idle  and  has  no  transportation  outlet  as  yet,  but 
it  is  only  a  half  mile  from  the  claim  of  the  Western  Carbonic  Acid 
Cas  Company,  which  has  a  wagon  road  to  Guerneville.  The  claims 
are  patented.     Estate  of  George  Madeira,  owner. 

Bibliography.  Cal.  State  Min.  Bur.,  Reports,  XIII,  p.  640;  XIV, 
p.  325;  Bull.  37.  p.  112;  Bull.  38,  pp.  114,  333,  369.  IT.  S. 
Geol.  Surv..  Bull.  355,  pp.  25.  26 ;  Bull.  540,  p.  497. 

y  W 

Meeker  Ranch  Deposit.  It  is  in  Sees.  2  and  3,  T.  8  N.,  R.  11  ^., 
M.  D.  M.,  seven  miles  by  road  north  of  Guerneville.  The  outcrop 
of  magnesite  is  close  to  the  top  of  a  knob,  between  Gilliam  and 
Rock  creeks,  known  as  Morrison  Ridge,  and  only  one  mile  S.  20  W. 
from  the  Western  Carbonic  Acid  Gas  Co.'s  mine,  described  below. 
The  magnesite  is  conspicuously  exposed  for  400  feet  continuously 
in  a  ledge  10'  to  40'  wide,  and  rising  15'  to  20'  above  the  soil.  This 
large  outcrop  contains  two  good  veins  4V  and  1^'  thick,  respectively. 
The  remainder  of  the  ledge  runs  northwest  and  is  vertical.  It  has 
l>een  prospected  by  a  small  cut  in  the  lower  side.     A  road  has  been 


92  CALIFORNIA    STATE   MINING   BUREAU. 

built  one-half  mile,  to  reach  it,  and  one  carload  was  shipped  out 
during  the  summer  of  1917.  Down  the  hill  towards  Gilliam  Creek, 
there  are  several  small  exposures.  It  is  estimated  that  probably 
5000  tons  of  ore  could  be  secured  from  the  surface  without  dead 
work.  The  only  disadvantage  is  the  haul  to  the  railroad,  two  miles  of 
which  is  up  hill.  The  property  was  taken  over  in  1916  by  the 
Guerneville  Farms  Company,  Jacobs,  Malcome  and  Burt,  managers, 
101  Washington  St.,  San  Francisco,  who  did  some  development  work, 
but  nothing  has  been  done  recently. 

Bibliography :  Cal.  State  Min.  Bur.,  Report  XIV,  p.  327 ;  Bull.  38, 
p.  333.     U.  S.  Geol..  Surv.,  Bull.  355,  p.  28. 

Melville  Ranch.  Magnesite  has  been  mined  spasmodically  for 
several  years  on  this  property,  formerly  the  Eckert,  and  later  the 
Yordi  ranch.  It  is  situated  two  miles  southeast  of  Cloverdale  on 
a  steep  hillside  just  above  the  valley  floor.  The  ore  consists  of 
boulders  of  magnesite  in  soft  serpentine.  The  boulders  are  in  fairly 
close  contact,  forming  an  orebody  which  averages  3  feet  in  thickness, 
but  varies  up  to  8  feet.  Its  course  is  N.  30°  E.  The  ore  is  white 
and  massive  with  some  'pop  corn'  structure.  It  is  said  to  carry 
about  3%  silica  and  no  lime.  Development  consists  of  an  open  cut 
75'  long,  and  18'  to  20'  wide  and  deep,  under  which  the  mining  has 
been  done.  A  tunnel  driven  N.  50°  E.  cut  the  'boulder  vein'  at  150'. 
30'  below  the  bottom  of  the  open  cut ;  it  then  followed  the  vein  for 
30  feet.  The  ore  was  taken  down  by  stoping  above  the  drift,  being 
mined  by  pick  and  shovel,  as  drilling  was  unnecessary.  W.  B.  Smith 
and  L.  C.  Stephens  of  Cloverdale,  lessees  during  1917,  shipped  sev- 
eral hundred  tons  of  crude  ore.  The  property  has  been  idle  since 
1918  or  1919. 

Bibliography :  Report  XIV,  p.  333 ;  Bull.  38,  p.  333.     U.  S.  Geol. 
Surv.,  Bull.  355,  p.  23 ;  Bull.  540,  p.  498. 

Snyder  Ranch.  There  is  said  to  be  an  undeveloped  deposit  of 
magnesite  on  the  George  Snyder  ranch  on  Piney  Creek,  about  12 
miles  southwest  of  Healdsburg. 

Bibliography:  Report  XVII,  p.  249. 

The  Sonoma  Magnesite  Company  (also  referred  to  as  the  Red  Slide 

Deposits)  owns  a  group  of  thirty  claims  on  East  Austin  Creek  in 
Sees.  6,  7,  8,  17  and  20,  T.  9  N.,  R.  11  W.,  M.  D.  M.,  6  miles  north  of 
Cazadero.  During  1914,  a  24"  gauge  railroad  was  laid  8  miles  on 
a  road  grade  from  a  spur  of  the  narrow-gauge  railroad  above  AVatson 
station  to  within  3  miles  of  the  camp.  The  ore  was  hauled  to  the 
railroad  by  motor  trucks.  The  company  also  erected  a  calcining 
plant  (see  Photo  No.  42),  with  a  capacity  of  30  tons  per  24  hours,  at 
the  property.  In  1917  a  second  furnace  was  added.  The  deposits 
were  worked  for  over  two  years  and  shipments  were  made  via  the 
Panama  Canal  to  New  York.  Operations  ceased  temporarily  in  the 
fall  of  1916,  on  account  of  financial  trou])les.  This  was  in  part  due 
to  the  excessive  transportation  costs,  its  product  having  to  be  handled 
three  times  after  leaving  the  property — (1)  the  3  miles  haul  to  the 
24"  tram,  (2)  the  8-mile  haul  to  the  narrow  gauge  at  Magnesia  sta- 


MAGNESITE   IN    CALIFORNIA. 


93 


tion,  (3)  transshipping  7  miles  l)eyond,  at  Duncan  Mills  to  the  broad 
uauge  Northwestern  racifie  Railroad — and  to  the  irregularity  and 
uncertainty  of  the  deposits  developed. 

There  are  three  groups  of  magnesite  outcrops  with  a  northwest 
trend  in  a  large  belt  of  serpentine.  The  principal  work  has  been 
confined  to  the  lower  group  in  Sec.  20.  Development  work  here 
consists  of  two  tunnels  and  a  large  open  cut.  The  lower  tunnel  was 
started  as  a  drift  on  the  outcrop  of  a  9-ft.  vein,  but  after  50  ft. 
turning  to  the  northeast  and  running  as  a  crosscut  for  almost  200 
feet,  where  a  small  step-faulted  vein  of  magnesite  was  struck.  The 
upper  tunnel,  50  feet  above  the  lower,  was  also  started  on  a  large 
outcrop,  but  driven  as  a  crosscut.  It  cut  veins  showing  Avidths  of 
12',  5',  15",  18",  and  8",  as  well  as  smaller  ones.     Some  drifting 


Photo  No.  40 — Vein  of  magne.sile,  as  exposed  in  an  open  cut  on  the  Alfred  claim 
of  the  Sonoma.  Magnesite  Company.  Dips  into  the  hill  (easterly)  at  a 
flat  angle. 


has  been  done  on  the  larger  veins,  but  most  of  the  work  was  done 
at  the  quarry  or  open  cut  below,  where  it  is  said  a  large  tonnage 
was  taken  out. 

At  the  upper  claims,  H  miles  northAvest  of  the  lower  workings,  a 
tunnel  was  driven  N.  48'  p].,  230  feet  ])elow  some  large  croppings  of 
magnesite  which  form  prominent  ledges  on  the  steep  slopes  above. 

Gale  in  his  report  ^  on  this  property  states : 

"The  exposure  higher  on  the  slope  consists  of  a  large  projecting  ledge  of  white 
magnesite,  wliich  makes  a  conspicuous  feature  in  the  thickly-forested  and  brush- 
covered  hillside.  The  thickness  and  attitude  of  the  ledge  are  difficult  to  di-termine 
from  the  present  exposure,  as  an  apparent  vein-handed  structure  dipping  40°  NE. 
is  most  evident  in  the  ledge,  and  yet  the  attitude  of  the  extension  of  this  massive 
ledge  to  the  soutlieast,  as  viewed  from  a  distance,  is  that  of  a  rather  steep  dip 
towards    the    creek,    or    southwest.      For    this    reason    the    section    measured    on    the 

'  Gale,  H.  S.,  Magnesite  deposits  in  California  and  Nevada :  U.  S.  Geol.  Surv..  Bull. 
r)40,  p.  493,  1914. 


94 


rAl.IFORNIA    STATE    MINING   BUREAU. 


outcrop,  giving  a  tliickness  of  :](»  to  35  feet  across  the  l)anded  structure,  very 
likely  does  not  represent  the  true  cross  section  of  tlie  vein.  Magnesite  constitutes 
a  very  large  part  of  the  mass,  however,  as  is  indicated  ))y  surface  exposures  and 
further  underground  exploration  of  the  deposit  will  be  necessary  before  its  limits 
can  be  more  positively  defined.  The  extent  of  tliis  deposit  in  either  direction  is 
also  a  matter  of  mucli  uncertainty.  A  ledge  similar  to  the  magnesite  outcrop  was 
observed  to  the  northwest,  and  evidently  the  ledge  extends  about  S.  30°  E.  from  the 
outcrop  that  was  examined  above  the  tunnel.  According  to  report  the  ledge  has 
been  traced  300  feet  to  the  north  and  400  feet  to  the  south,  but  the  deposit  is 
supposed  to  be  thickest  near  the  center. 

"The  magnesite  of  both  the  upper  and  lower  claims  appear  to  be  of  similar 
character.  The  outcrop  consists  of  rough  weather-stained  rock.  *  *  *  Where 
the  rock  is  liroken  off,  the  magnesite  shows  a  chalky  white  surface,  in  patches 
having  the  typical  white  china-like  fracture,  but  the  mass  is  irregularly  broken  or 
jointed  and  filled  with  seams  and  cavities  lined  with  silica." 

Later  developments  (see  Photo  No.  40)  by  open  cut  on  the  vein 
show  that  it  does  dip  into  the  hill  (easterly),  as  suggested  by  Gale, 
above.    Its  thickness  is  at  least  20  feet  at  that  point. 


Photo   No.   41 — Ore  chute  at  upper  deposit  of   Sonoma   Magnesite  Company. 


MAGNESITE    IN    CAUFORNIA. 


95 


The  followino-  analyses  of  samples  from  the  ui)per  and  lower  claims 
are  taken  from  an  earlier  -  report. 


Sample  From 

SiO, 

AljOs 

FesO, 

CaO 

MgO 

CO, 

MgCO. 

Vndeter- 
mined 

'  Cecilia   (upper  tunnel, 

lower  o!aim.«) 

'  Ceeilia  (lower  claims  J  _  - 

•  Alfred  (upper  claims)  .  . 

'  Alfred  (upper  claims) , . 
^  Vera  Xo.  2  (Calcined 

upper  claims) 

'  Alfred  (Calcined  upper 

7.67 
3.66 

'2.50 

2.50 

0.74 

6.66 

7.85 

0.26 
0.75 

0 

0.29 
0.44 

.55 

9 

0.04 
0.20 

'2.30 

Xone 
0.52 

43.42 
44.90 

46.0 
94.21 
82.60 
87.31 

48.08 
49.20 

«49.3 

93.92 

0.24 

0.85 

/0.36\ 

»\0.37/ 

5.05 

10.22 

0.21    1        4.63 

=  Vera    (Calcined   upper 

'  Analysis  by  .\.  J.  Peters,  (U.  S.  Geological  Survey). 
-■  Anaiysis  by  W.  C.  Wheeler  (L'.  S.  Geological  Survey). 
'  Anaiysis  by  StaufFer  Chemical  Co.,  San  Francisco. 
•  Anaiysis  by  Selby  Smelting  and  Lead  Company. 
5  Anaiysis  by  Booth,  Garrett  and  Blair,  Philadelphia,  Pa. 


'  Silicates. 

'  Calcium  carbonates. 

'  Calculated. 

'  Moisture. 


PHdTO  No.   42 — Rotary  kiln  of  Sonoma  Magncsite  Co..  at  'MagiU'siu 


monia  t'ounty. 


The  .sueeessful  exploitation  of  this  i)roperty  depends  on  several 
factors,  mainly  reduced  transportation  costs  and  skillful  manaurement. 
Considerably  more  development  Avork  should  he  undertaken  upon  the 
larger  veins  to  determine  whether  they  are  pei-sistent  or  merely 
erratic   deposits.     Early   in    1924.   the   property   was   taken   over   by 

=  Bradley,  W.  "W.,  Mines  and  mineral  re.sources  of  Colusa,  et  al,  counties:  chap- 
ters of  State  Mineralosist's  report,  biennial  i>eriod.  1913-1914,  Cal.  State  Min.  Bur., 
p.  159;  also  in  Report  XIV,  p.  331,  1916. 


96 


CALIFORNIA    STATE    MINING   BUREAU. 


Spreckels  Bros,  of  San  Diego,  and  some  development  work  carried  on, 
hut  there  has  been  no  production  since  1920. 

Bibliography:  Cal.  State  Min.  Bur.,  Report  XIV,  pp.  327-331; 
Bull.  38,  p.  333;  Bull.  66.  pp.  58,  59;  Bull.  71,  pp.  48,  49;  Bull. 
74,  pp.  68.  69 :  Bull.  83,  p.  69.  U.  S.  Geol.  Surv.,  Bull.  355,  p.  26 ; 
Bull.  540,  pp.  490-495. 

Western  Carbonic  Acid   Gas   Company,   Chas.   S.  Harker  Estate, 
owner;  c/o  E.  W.  Harker.  Porterville.   Cal.     The  company  owns  a 


Photo  No   43 — Calcining    furnace    of    AVestern    Carbonic    Acid 
Gas  Company,  at  Guerneville,  Sonoma  County. 

group  of  claims  at  the  head  of  Gilliam  Creek,  in  Sec.  6,  T.  8  N.. 
R.  10  W.,  M.  D.  M.,  7  miles  north  of  Guerneville.  A  wagon  road  has 
been  built  to  the  claims,  but  very  little  ore  has  been  shipped  out. 

The  magnesite  occurs  in  the  form  of  veins  in  serpentine  and 
detached  blocks  that  vary  up  to  100  tons  in  size.  At  the  end  of  the 
road  there  is  a  cropping  30  feet  high  on  the  loAver  side,  8'  to  12'  thick, 
and  40  feet  long.  All  of  the  ore  shipped  to  date  was  furnished  by 
breaking  up  an  80-ton  boulder.  Near  the  loading  platform  a  tunnel 
driven  38  feet  to  the  northeast  cut  a  3-foot  ledge  dipping  30°  E.    The 


MAGNESITE    IN    CAIJFORNIA.  97 

vein  is  faulted  and  offset  nearly  its  full  width.  Further  up  the  hill, 
tliere  are  several  exi)osures  of  niagnesite,  l)ut  they  have  not  been 
develoi)ed.  There  are  ])ro])ably  75  tons  on  the  stock  pile,  and  there 
could  easily  he  i-ecovercd  from  the  boulders  and  the  larjjfe  ledge, 
.15()()  tons  or  more.  A  stack  kiln  5  feet  inside  diameter  and  29  feet 
high  was  built  in  October,  1917,  at  Guerneville  to  burn  this  ore.  (See 
Photo  No.  -43.)  Work  at  the  mine  had  been  resumed  by  the  company 
that  summer,  but  only  a  few  men  were  employed.  A  few  carloads 
of  ore  was  hauled  down  to  the  plant,  but  work  ceased,  following 
the  decease  of  Mr.  Harker. 

The  plant  at  Guerneville  was  designed  to  produce  the  re-precipi- 
tated light  carlionate,  or  'magnesia  alba,'  as  well  as  the  ordinary 
magnesia. 

Biblio(jraphij:  Cal.  State  Min.  Bur.,  Report  XIV,  p.  332.     U.  S 
Geo'l.  Surv..  Bull.  355,  p.  2-4;  Bull.  540,  pp.  495-497. 


7—39802 


98  CALIFORNIA    STATE    MINIX(i    BTREAU. 

STANISLAUS  COUNTY. 

iMagnesito  deposits  are  now  being  developed  on  the  east  slope  of 
Red  Mountain,  whose  suniniit  marks  the  division  between  Stanislaus 
on  the  east  and  Santa  Clara  County  on  the  west,  and  it  is  prol)al)lc 
that  other  deposits  occur  in  the  brush-covered  and  little-traversed 
hills  to  the  south.  The  Red  Mountain  deposits  of  the  east  slope  have 
been  located  for  many  years,  but  it  was  not  until  1936  that  an>' 
attempt  was  made  to  develop  them.  This  was  due  to  the  comple- 
tion of  the  Patterson  and  Western  Railroad  to  the  foot  of  Red  JMoun- 
tain  which  made  them  easily  accessible.  Though  that  railroad  has 
now  been  discontinued  and  the  rails  taken  up,  the  road-grade  is  being 
utilized  for  auto-truck  hauling.  Another  series  of  deposits  has  also 
been  opened  up  on  Quinto  Creek  in  the  southwestern  corner  of  the 
county  near  the  JNIerced  County  line  west  of  Ingomar. 

Bald  Eag-le  Claim.  This  claim,  in  Sec.  82,  T.  8  S.,  R.  7  E.,  M.  D.  M., 
was  located  by  A.  D.  Davenport,  of  Gustine,  and  was  operated  under 
lease  in  1917,  by  the  Gustine  ^lagnesite  Comj^any,  as  described  below. 

Geo.  V.  Borchsenius,  of  Patterson,  reports  that  he  has  a  group  of 
claims  on  a  magnesite  deposit  in  the  Arroyo  del  Puerto  district  neai- 
the  Red  Mountain  mine,  west  of  Patterson. 

California  Magnesite  Co.  (Red  Mountain  Mine)/  G.  A.  Scott, 
president ;  M.  W.  Kirk,  secretary ;  home  oftice.  Fifth  and  Parker 
Streets  (Blanding  Iron  Works),  Berkeley,  J.  Frame,  superintendent, 
Patterson,  California.  This  mine  is  situated  on  the  Stanislaus  County 
side  of  Red  Mountain  in  Sec.  20,  T.  6  S.,  R.  5  E'..  at  an  elevation  of 
2500'.  There  is  no  timber  but  considerable  brush.  A  large  spring 
supplies  all  the  water  needed. 

The  property  consists  of  four  claims  and  a  mill  site,  a  total  of 
about  S5  acres.  The  deposit  was  discovered  in  1915  by  James  and 
Plunket.  The  original  company  was  known  as  the  Red  INIountain 
Magnesite  Co.  Later  it  was  called  the  W-K  Co.  In  January,  1922, 
it  was  reorganized  as  the  California  Magnesite  Company. 

The  deposit  consists  of  parallel  lenses  of  high-grade  magnesite 
in  serpentine  country  rock,  of  which  Red  ]\Iountain  is  composed. 
Operations  have  been  by  glory  hole  and  stoping  from  the  main  tunnel 
level.  Two  lenses  18'  and  25'  wide,  respectively,  at  the  tunnel  level 
have  been  stoped  from  there  to  the  surface.  The  main  tunnel, 
which  is  1300  feet  in  total  length,  has  apparently  cut  the  top  of  two 
other  lenses.  The  orebodies  strike  N.  20  W.  and  dip  about  85 
into  the  mountain.  The  total  production  since  the  mine  was  opened 
up  has  been  approximately  50.000  tons.  This  was  calcined  in  part 
at  the  mine  and  also  at  the  calcining  plant  of  the  ]\lineral  I'roducts 
Co.  in  Patterson,  which  Avas  taken  under  lease.  The  calcining  equip- 
ment at  the  mine  consists  of  a  shaft  fui-nace  of  15-tons  daily  capacity 
and  a  small  rotary  furnace  used  mainly  for  burning  tines.  Crude 
oil  is  used  for  fuel.  ISUne  equipment  consists  of  two  70-h.  p.  boilers, 
a  7-drill  Ingersoll-Rand  compressor,  steam  hoist  and  pumps  for 
handling  the  water  supply,  and  fuel  oil.     There  is  also  a  25-h.  p.  gas 

'From  manuscript  of  C.  McK.  Laiziiie,  in  ':Miiiing:  in  California.'  .A.pril,  lOl'i. 
Report  XXI  of  State  Mineralogist. 


MAGNESITE    IN    CALIFORNIA.  99 

engine  and  2-dnll  Sullivan  compressor,  ears,  track,  etc.  The  eanip 
buildings  will  accommodate  about  30  men. 

Practically  all  ore  above  the  present  adit  was  taken  out  and  the 
mine  was  shut  down  in  September,  1923,  pending  additional  develop- 
ment. Another  adit  about  2o(y  below  the  upper  one  had  just  been 
started  to  cut  the  orebodies  exposed  in  the  upper  adit.  This  adit 
will  have  to  be  driven  about  900  feet  to  reach  the  ore. 

Negotiations  are  now  under  way  looking  to  the  immediate  comple- 
tion of  the  new  adit  and  resumption  of  full  operations.  It  is  probable 
that  this  move  will  include  taking  over  the  calcining  plant  of  the 
Mineral  Products  Co.  at  Patterson,  and  possibly  the  moving  of  the 
90-foot  rotary  kiln  with  which  it  is  equipped  to  the  mine  as  it  has 
proved  more  economical  to  burn  the  magnesite  at  the  mine  than  to 
transport  the  crude  material.  The  road  bed  of  the  former  Patterson 
and  Western  R.  R.  which  ran  from  Patterson  to  the  foot  of  Red 
jMountain,  makes  an  excellent  graded  road  for  auto-truck  hauling 
to  Avithin  a  short  distance  of  the  mine,  so  that  the  pi'operty  is  not 
difficult  of  access. 

G.  L.  Fenster  et  al.,  Patterson,  C'al.,  own  a  group  of  five  claims  in 
Sec.  22,  T.  ()  S.,  R.  5  E.,  M.  D.  M.,  adjoining  the  Red  iMountain  magne- 
site mine.  There  are  several  croppings  of  massive  white  magnesite 
on  the  claims,  the  most  promising  of  which  is  on  the  Last  Chance 
claim.  The  ledge  here  is  nine  feet  thick,  and  appears  to  be  quite 
extensive.  There  has  been  as  yet  practically  no  development  work 
done  on  this  group,  h^nce  the  commercial  importance  of  the  deposits 
is  only  prospective. 

Gustine  Magnesite  Company.  In  1917,  this  company  composed 
mainlv  of  Oakland  men.  operated,  under  lease,  the  Bald  Eagle.  Quinto 
and  other  claims  in  Sec.  32,  T.  8  S.,  R.  7  E.,  M.  D.  M.  They  are  on 
Quinto  Creek,  16^  miles  west  of  Ingomar,  and  near  the  Merced 
County  line.  The  ground  of  the  Howard  Cattle  Company  adjoins 
on  the  south  (see  Photo  No.  44),  in  fact  both  properties  are  located 
on  th(^  same  ore-zone,  the  township  line  running  diagonally  across 
the  area  shown  in  the  photograph  from  the  lower  left  corner  to  the 
upper  right.  The  top  of  the  ore-loading  bunker  of  the  Gustine  com- 
|)any  is  just  visible  in  the  ravine  at  the  left. 

The  company  began  operations  in  June,  1917,  opened  up  the  ore- 
body,  and  continued  shipments  for  several  months,  closing  down 
early  in  1918.  The  cessation  was  apparently  due,  in  part  to  the 
difficulty  of  keeping  the  workings  open,  and  in  part  to  their  neai'ing 
the  property  line,  as  there  is  still  a  good  body  of  ore  showing  where 
stoping  was  stopped.  The  magnesite  is  in  the  form  of  irregular 
segregations  in  a  soft,  decomposed  serpentine  material.  They  began 
stoping  from  the  main  adit  as  they  drove  in;  and  the  nature  of  the 
ground  made  it  necessary  to  tind)er  heavily  to  keep  the  tunnel  open. 
When  visited,  in  June,  li)18.  the  Avails  had  closed  in  at  some  points 
so  that  it  would  have  been  difficult  to  run  an  ore  car  through. 

Some  of  the  ore  shipped  from  this  j)rojierty  showetl  the  higiiest 
l)urity  yet  recorded  foi-  magnesite  in  California,  analysis  indicating 
a  total  of  less  than  1%  of  impurities.  The  General  Electric  Com- 
luiiiy.  Schenectady,  New  York,  bought  some  of  this  magnesite  paying 


100 


CALIFORNIA    STATE    MINING   BUREAU. 


t     3 


MAQNESITE   IN    CALIFORNIA. 


101 


as  high  as  $25  per  ton,  f.  o.  b.,  Ingomar,  for  at  least  one  carload  of 
sorted  material.  Some  was  also  sold  at  $17.o0  per  ton,  Avhieh  was 
about  $5  per  ton  over  the  then  (Jiil.v,  1!)17)  quoted  price  for  crude 
material,  f.  o.  b.  rail.  They  utilized  a  part  of  it  in  the  preparation 
of  magnesium  metal  by  electric-furnace  reduction,  and  a  part  as  an 
insulation  powder  for  certain  electrical  installations. 

This  property  was  idle  in  1918-1919,  but  operated  in  1920-1921 
by  the  Plastic  ^lagnesite  Company  of  San  Francisco.  The  Gustine 
Company  shipped  a  total  of  approximately  2000  tons  of  crude  oi-c 
during  their  operations. 

Bibliography:  Cal.  State  Min.  Bur.,  Report  XVII,  p.  254. 

The  Howard  Cattle  Company,  Sharon  Bldg.,  San  Francisco,  is  the 
owner  of  Sec.  5,  T.  9  S.,  R.  7  E.,  M.  D.  M.,  which  contains  the  con- 
tinuation of  the  magnesite  deposits  opened  up  on  the  adjoining 
Sec.  32  by  the  Gustine  ^Magnesite  Company,  as  described  in  the  pre- 
eeeding  paragraphs.    They  are  on  Quinto  Creek.  16^  miles  west  from 


Photo    No.    45 — Magnesite   loailing-bunkers    at    Ingomar,    for    the    Gustine    Magnesite 
and  Howard  Cattle  Company    mines. 

Ingonuir,  the  shipping  point  on  the  Southern  Pacific  Railroad.  When 
visited  in  June.  1918,  this  property  was  being  operated  by  J.  S. 
^Middleton,  lessee,  with  N.  J.  Miller  as  contractor  on  the  mining  of 
the  ore. 

The  magnesite  occurs  in  the  form  of  irregular  segregations  in  an 
area  of  soft,  decomposed  serpentine.  Some  of  the  magnesite  is  clean, 
liard,  and  white,  and  part  of  it  is  somewhat  powdery,  though  this 
latter  was  stated  also  to  be  high  grade.  In  places,  above  the  main 
orebody,  disseminated  pellets  of  magnesite  were-  noted  in  the  ser- 
pentine. There  are  some  faults,  l)ut  none  of  them  have  apparently 
caused  any  consideral)le  disi>lacement.  The  ore  has  been  stoped,  in 
places  up  to  12  fe(^t  wide.  The  method  adopted  has  been  to  drive 
to  the  ])ack  of  the  orebody,  then  fill  behind  as  the  ore  was  stoped 
Dut.  This  obviated  the  timbering  difficulties  experienced  by  their 
neighbors. 

The  lessees  began  shipping  on  December  1,  1917,  hauling  the  crude 
magnesite  by  motoi-  trucks  to   Ingomar   fsce  l^lioto  No.  45),  thenc*- 


102  CALIFORNIA    STATE    MINING    BUREAU. 

hy  rail  to  the  plant  of  the  Sedan  Calcined  Ma^nesite  Company  at 
P^niervville,  Cal.  A  total  of  over  1000  tons  was  shipped  up  to  the 
end  of  1918.    Idle  since  1919. 

A  sample  of  the  calcined  magnesite  has  been  presented  to  the 
]\Iuseuni  of  the  State  Mining  Bureau,  by  ^Mr.  Frank  Maestretti  of 
the  Sedan  Company,  accompanied  by  the  following  analysis : 

Analysis  of  Calcined  Mafjnesite. 

Silica    (SlO^i) l.ns% 

Iron    and    Alumina    (R2O3) 0.40% 

Lime    (CaO)    2.02'/, 

Magnesite    (MgO),    by    difference 95.60% 

Ignition    loss    0.90% 

100.00% 

Quinto  Claim.  This  claim,  located  by  E.  S.  Kingslev  of  Gustine. 
is  in  Si  of  See.  32,  T  8  S.,  R.  7  E.,  M.  D.'  M.,  and  was  worked  in  1917 
by  the  Gustine  Magnesite  Company,  as  described  above. 

Chas.  Schindler  reports  that  he  has  a  group  of  claims  on  a  deposit 
of  magnesite  in  the  Arroyo  del  Puerto  district  west  of  Patterson. 


MAGNESITE    IN    CALIFORNIA. 


103 


TULARE  COUNTY. 

In  tlie  ])i'<)(liU'tioii  of  iiiaj^iicsitc,  Tnlai'e  has  been  the  premier 
couiily  of  the  state,  and,  as  California  is  the  oiily  coniinonwcalth  in 
the  I'nited  States,  ('xcej)t  Washington,  from  whieh  domestic  snpplies 
are  derived,  tlie  ontput  became  of  national  significance,  particularly 
during  the  period  of  the  war,  when  foreign  impoi'ts  Avere  curtailed 
oi-  completely  cut  off. 

The  output  from  Tulare  County  for  the  record  year,  li)17,  amounted 
to  136,ri()2  tons,  valued  at  51^1,238,853,  a  tonnage  exceeding  several 
times  over  that  of  the  next  largest  eontributoi-. 


Photo    No.    46 — Magnesite   vein    3    feet   thick,    in   No.    3    workings    of    I^indsay   mine, 
near  Success,  Tulare  County.     Shows  effect  of  shearing. 


An  estimate  of  the  monthly  i-ate  of  ])iH)du('tion  of  calcined  magne- 
site in  the  Porterville  district  during  Ai)ril,  llHT,  was  as  follows: 

American     Magnesite    Co '25()0  tons  per  mo. 

Porteivillf   Magnesite   Co 2750  tons  per  mo. 

Tularo    Mining    Co 1200  tons  per  mo. 

Other   shipments    1600  tons  per  mo.    (3320   tons  crude) 

Total   SUO   tons  per  mo. 

Based  on  the  prevailing  i)i'ice  of  .'1^32. ')()  per  ton  for  calcincHl 
material,  this  was  etniivalent  to  a  montlih-  |)roduetion  \alue<l  at 
.^259,520. 

The  center  of  the  magnesite  mining  industi-y  is  near  I'orterville 
in  the  i-aiige  of  foothills  of  the  Sierra  Nevada,  east  and  northeast 
of  the  city.  .Magnesite  deposits  a  short  distance  northeast  of  Porter- 
ville were  discovered  as  early  as  1853,'   but  active  operations  were 

'Report  XV   of  State   Mineralogist,   p.    1122.    IIH.')-,    also   Ueport    XN'II,    p.    259,    1920. 


CALIFORNIA    STATE    MINING   BUREAU 


MAGNESITE    DEPOSITS 

IN    THE    VICINITY    OF  ' 

PORTERVILLE.  TULARE  CO..  CAL. 

bcale  of  miles 


1925 

CALIFORNIA  STATE  MININS  BUREAU 

Lloyd  L  Root, State  Mineralogist 


MAGNESITE    IN    CAT>IFORNIA. 


lOo 


unimportant  until  IDUU.  Tlie  main  deposits  are  east  of  Porterville, 
Lindsay  and  Exeter,  these  being  the  railroad  points  from  which 
sliipments  are  made.  Smaller  occurrences  extend  southerly  to  a 
point  east  of  Terra  Bella,  and  northwesterly  to  the  St.  John  river 
near  Kaweah.  In  general  direction  the  deposits  parallel  the  South- 
ern Pacific  and  Santa  Fe  railroads  at  distances  of  from  one  to  ten 
miles. 

The   geology  has   liecn   fully   covered  in   the   descriptions   of  the 
Porterville  deposits  by   Hess^   and   Gale."  and  the   subject  has  been 


I'HOTO  No.   47 — Slickensitled  magnesite  showing  effect  of  movement 
along  the   vein,   in  tunnel   of   Lindsay  Mining  Company. 

briefly  treated  in  the  chapters  of  the  State  Mineralogist's  Report 
(1916)  devoted  to  the  Mines  and  Mineral  Resources  of  Tulare 
County.''     The  following  excerpts  are  taken  from  the  last  named: 

"The  magnesite  occurs  in  a  schistose  serpentine  mass  which  is  Impregnated  with 
magnesite  veins  and  contains  some  basalt  and  diabase  intrusions.  The  country 
rock   is   a   dull,   brown,    serpentinized   peridotite.      The    rock   is   sheeted   in   places   and 


'  Me-ss,  F.  L.,  The  magnesite  deposits  of  California:  U.  S.  Geol.  Surv.,  Bull.  355, 
pp.:?!)-4!l,    190S. 

-Gale,  II.  S..  Late  dcvi-lopmeiits  of  magnesite  tleposits  in  California  and  Nevada: 
U.  S.  Geol.  Sur\.,   Hull.   ".  H),  pp.  50'J-51L   1914. 

"Tucker,  W.  B..  Mines  and  mineral  resources  of  Tulare  County:  Cal.  8tate  Min. 
Bur.,  pp.   14S,   149,   1916;  also  in   Report  XV,  pp.  922-923. 


106  CATJFORXIA    STATE    MINING    BT'REAT. 

fontains  givat  numbers  of  veitical.  thin  iianillel  \fiii.s  of  magnesite.  Crossing  the 
vertical  veins  at  a  small  angle  is  a  second  series  of  veins,  and  a  third  series  crosses 
at  right  angles.  *  *  *  The  veins  are  proV)ably  due  to  shearing,  which  caused 
cracks.  These  cracks  then  formed  cliannels  for  surface  waters  and  were  filled  with 
magnesite  derived  from  the  decomposition  of  the  enclosing  rock  and  brought  by 
waters  from  a  distance  and  precipitated.  The  veins  are  generally  discontinuous 
and  irregular,  and  of  narrow  widths." 

Adeline  Magnesite  Mine.  E.  F.  Schrei,  Lindsay,  owner.  The  mine 
is  in  See.  24,  T.  20  S.,  R.  27  E.,  I\r.  D.  M.,  6i  miles  east  of  Lindsay 
and  7i  miles  due  north  of  Porterville.  Schrei  also  owns  the  Oinesra 
and  Frisc'illa  claims  in  the  same  Sec.  24.  and  the  Keokuk  claim  in 
Sec.  20.  T.  20  S.,  R.  28  E.  There  is  a  tunnel  in  252  feet,  alone-  a 
maiinesite  vein  from  1'  to  4'  Avide,  strikes  east  and  dips  40"  X. 
There  are  also  several  promising'  surface  showings,  consisting  of  veins 
from  V  to  2'  wide.  During  the  war,  lessees  who  operated  this  prop- 
erty made  shipments  totaling  50  cars  of  crude  ore.  After  lying  idle 
since  the  war  period,  Schrei  advises  us  (March,  1925),  that  develop- 
ment M'ork  is  again  under  Avay  and  that  Los  Angeles  parties  have 
organized  under  the  name  of  El  IMirador  Magnesite  Company  to 
operate  the  property.  It  is  proposed  to  build  a  shaft  kiln  at  the 
mine. 

American  Magnesite  Company   (see  Sierra  Magnesite  Company). 

This  plant,  built  originally  by  the  California  ^Magnesite  Company,  was 
taken  over  in  1916  by  the  American  ^Magnesite  Company  and  operated 
(luring  the  Avar  as  a  custom  plant  for  the  calcining  of  magm^site  for 
the  American  Refractories  Company  of  Joliet.  111.  It  Avas  sold  to  the 
Sierra  IMagnesite  Company  in  1920.  • 

The  Blue  Crystal  Magnesite  Group  is  in  Sec.  24.  T.  20  S..  R.  27  E.. 
iM.  D.  M.,  64  miles  southAvest  of  Lindsay.  There  are  four  claims  and 
a  fraction,  (Blue  Crystal  No.  1  and  No.  2,  YelloAv  jNIetal,  Kaolin  King, 
and  AVestern  Fraction),  Avhich  are  located  on  the  Avestern  slope  of  a 
hill  on  the  east  side  of  the  mouth  of  Round  Valley,  at  an  average 
elevation  of  950  feet.     There  is  no  timber  on  the  property. 

A  number  of  strong  veins  of  magnesite  of  A-ery  good  quality  out- 
crop in  serpentine.  Three  of  these,  about  fifty  feet  apart,  approxi- 
mately parallel,  strike  northAvest,  Avith  steep  dips,  and  have  been 
opened  up  by  open  cuts  and  tunnels,  using  hand  labor,  a  considerable 
amount  of  crucle  ore  having  been  shipped.  During  the  Avar  period 
an  average  of  15-20  men  Avere  employed.  Tavo  cars  per  Aveek,  or 
800  tons  per  month,  Avere  the  usual  shipments.  Transportation  from 
the  mine  to  the  railroad  cost  $1  per  ton  and  the  freight  tariff  to 
San  Francisco  Avas  $8  per  ton.  The  Avorkings  in  1917  included  the 
folloAving : 

Open  cut  20'  deep  by  35'  long.  16-inch  vein  of  No.  1  magnesite, 
strike  N.  40°  W.,  dip  85°  NE.  A  100'  tunnel  at  an  elevation  of  950 
feet  cuts  a  parallel  vein  at  80'  Avhich  is  12  inches  Avide.  This  tunnel 
Avill  ap])arently  cut  a  80-inch  vein  exposed  on  the  surface  about  20 
feet  farther  and  develop  TOO'  of  l)acks. 

Another  80-inch  vein  exposed  on  top  of  the  hill  cuts  across  these 
in  an  easterly  direction.  An  80-foot  open  cut  has  been  made  along 
the  vein  and  all  ore  taken  out  to  a  depth  of  30  feet. 

A  140-foot  tunnel  at  an  elevation  of  1000  feet  folloAvs  an  18-inch 
vein  Avhich  splits  into  tAvo  veins,  a  12-inch  and  a  80-inch.  Tavo  other 
12-inch  veins  parallel  this  and  are  open  10'  deep  and  80'  in  length. 


MAGNESITE    IX    (AIJFORNIA.  107 

The  surface  of  the  top  of  the  hill  shows  a  network  of  veins  from 
3  inches  to  4  feet  wide  and  a  trench  at  an  elevation  of  1200  feet  cuts 
throuirh  the  top  of  the  hill  on  a  80-inch  vein  running-  E.  The  trench 
is  25'  deep  and  50'  long:.  The  crest  of  the  hill  could  probably  be 
(|uarried  20'  x  50'  by  20'  deep  and  10%  of  the  material  shipped. 

The  Blue  Crystal  :Magnesite  Group  is  oAvned  by  S.  A.  Hougs, 
Lindsay.    There  has  been  no  production  the  past  two  or  three  years. 

Bihliugraphij:  Cal.  State  Min.  Bur..  Report  on  mines  and  mineral 
resources'of  Tulare  Co..  Dec.  1916:  also  Reports  XV,  p.  92-t; 
XVIII,  p.  531. 

California  Magnesia  Company  (see  Harker  Mine). 

Chamberlain  Ranch  Deposits.  These  deposits  are  on  the  Chaml)er- 
lain  raneh.  8  miles  southeast  of  Porterville,  in  Sees.  3  and  10,  T.  23 
S.,  R.  28  E.,  ]\I.  D.  M.  On  the  west  slope  of  a  hill  which  runs  in  a 
northwesterly  direction,  there  are  numerous,  narrow  and  irregular 
veins  varying:  in  width  from  6  inches  to  12  inches.  During  1916, 
the  property  Avas  under  lease  to  the  California  ?klagnesite  Company. 
Idle.  Selah  Chamberlain,  San  Francisco,  OAvner. 
BihliograpJni :  Report  XV.  p.  926. 

Cross  Ranch  Deposit  (Burr  Bros.  Lease).  IMrs.  Fhn-ence  Cross, 
owner.  Located  3  miles  north  of  Lindsay,  in  See.  19,  T.  19  S.,  R.  27 
E.,  :\I.  1).  M..  on  a  Ioav  hill  at  the  edge  of  the  valley,  AAdiere  a  large 
num!;er  of  magnesite  veins  occur,  more  or  less  parallel,  with  north- 
east strike.  The  veins  are  narroAv  and  irregular,  Avith  steep  dips, 
but  do  not  shoAv  c(mtinuity.  A  number  of  tunnels  Avere  driven  on 
tile  veins,  from  50'  to  100'  in  length,  and  ore  also  extracted  along 
the  outcrops  in  several  open  cuts.     Idle  since  the  Avar. 

BlbliograpJnj :  Report  XV,  p.  926. 

Deer  Creek  Mine  (also  kno\A'n  as  Langley-Cook  Lease).  It  is  on  the 
Carroll  raneh.  in  Sec.  21,  T.  22  S.,  R.  28  E.,  M.  D.  :\I..  8  miles  south- 
east of  Porterville.  On  the  north  slope  of  a  hill  south  of  Deer  Creek, 
there  are  numerous,  comparatively  thin  A'eins  of  magnesite  cutting 
a  dull-ln-OAvn  serpentinized  i)eridotite.  The  rock  is  sheeted  in  i)laces, 
and  the  magnesite  veins  .stand  nearly  vertical,  being  parallel  and 
varying  in  Avidth  from  10  inches  to  2  feet.  The.v  are  generally  dis- 
continuous and  irregular. 

The  veins  have  been  mined  l)y  a  number  of  open  cuts  and  tunnels 
on  both  the  east  and  Avest  slopes  of  the  hill.  In  the  tunnel  on  the  east 
slope,  a  shaft  has  been  sunk  near  the  portal,  on  the  vein.  Formerl.v 
operated  under  h^ase  by  J.  ^V.  Langley  and  11.  ?].  Cook  of  Los 
Angeles.  Avho  sbipj)ed  considerable  ore;  but  has  noAV  been  idle  for 
several  years.     Cbas.  Can-oil.  Deer  Creek.  OAvner. 

Bibliofjraplni :  n('])o\\  XV.   p.  927.     V.  S.  Ceol.   Surv.,  Bull.  355. 
PI).  39,  40. 

De  Moulin  Mine  (formerly  Magnesite  Refractories  Co.;  also  known 
as  Stewart  Mine).  This  i)i'opeit\"  eontaiiis  KiO  aei-es  pui-ehas<'d  from 
Ceo.  N.  Stewart,  in  the  X.l  of  Se"e.  12.  T.  21  S.,  R.  27  E.,  .M.  D.  M.  It 
is    directlv    north    of    Porterville    antl   onlv    al)out    3.1    miles   distant. 


108  CALIFORNIA    STATE    MINING   BUREAU. 

Some  of  tlio  inasnesite  opened  np  on  this  property  is  hydrated  and 
of  rather  low  grade,  other  portions  consist  of  No.  1  ovo.  The  country 
roek  is  serpentine.  Mining  has  l)een  done  by  luind  hil)()r,  and  the 
ore  shipped  crude.  An  ore  bin  and  chemical  lal)oratory  were  built, 
and  in  1916-1917  six  men  were  employed.  The  production  for  1916 
was  3648  tons  which,  sold  for  $8  per  ton. 

On  the  south  side"  of  the  hill  at  an  elevation  of  780  feet,  a  400-foot 
tunnel  shows  a  north  shoot  and  raise  to  the  surface  on  a  vein 
3'  to  4'  wide,  by  50'  deep  and  80'  long.  This  ore  is  more  or  less 
hydrated  and  is  of  low  grade  and  mixed.  The  same  vein  is  exposed 
on  the  north  side  of  the  hill  in  the  400-foot  main  tunnel. 

A  6'  to  10'  vein  was  stoped  for  250'  with  125'  of  backs.  Other 
development  consists  of  two  ore  chutes  and  four  raises.  This  main 
vein  strikes  N.,  with  vertical  dip,  and  the  ore  is  more  or  less  hydrated. 
It  is  planned  to  run  a  lower  tunnel. 

"Workings  on  the  south  side  include  a  20-foot  prospect  tunnel 
showing  a  vein  4'  to  5'  wide  carrying  15-20%  SiO, ;  also  two  cross- 
cut adits.  An  open  quarry  run  in  for  100'  at  an  elevation  of  800' 
showed  in  the  floor,  ore  10'  to  15'  wide  striking  N.  30°  E.  Lenses 
of  magnesite  lead  oflP  and  large  blasts  were  used  to  loosen  the  rock. 
This  ore  is  high-grade.  About  100  feet  of  short  tunnels  open  up 
low-grade  veins  from  4'  to  25'  wide. 

The  property  has  been  idle  for  several  years,  and  is  now  owned 
by  Edward  De  Moulin,  833  Security  Bldg..  Los  Angeles,  formerly 
president  of  the  Magnesite  Refractories  Company. 

BihJiographij :  Report  XV,  p.  936. 

Diirnba  Magnesite  Company  (Weissman  Lease).  From  a  hill  near 
Dinuba  on  the  Southern  Pacific  railroad,  near  the  Tulare-Fresno 
county  line,  the  Dinuba  ]\Iagnesite  Company  reports  having  shipped 
2500  tons  of  magnesite  during  1916.     Owner,  J.  J.  Sullivan,  Dinuba. 

Dumont  Magnesite.  The  Dumont  property  consists  of  1240  acres 
of  patented  land  located  about  five  miles  east  of  Exeter  in  the  rolling 
foothills.  A  few  scattered  oak  trees  grow  on  the  flats.  The  magne- 
site is  exposed  near  the  crest  of  a  large  hill  in  Sec.  10,  T.  19  S.,  R. 
27  E.,  M.  D.  M.,  as  veins  in  the  serpentine.  The  most  prominent 
vein  has  a  width  of  4  feet.  It  strikes  N.  60°  W.  and  dips  65°  NE. 
The  ore  is  hydrous  and  high  in  silica.  Ore  is  exposed  by  an  open 
cut  10'  deep  and  120'  long  on  the  crest  of  the  hill.  Below,  a  tunnel 
along  the  vein  shows  it  to  be  10"  wide,  30'  deep  and  75'  long.  A 
still  lower  tunnel  had  not  been  driven  far  enough  to  cut  the  vein 
and  the  total  ore  in  sight  was  estimated  at  1915  tons,  when  visited 
in  1917.  Shipments  totaling  several  hundred  tons  crude  were  made 
by  lessees  in  1916-1917;  but  the  property  has  been  idle  since  1918. 
W.  D.  Dumont,  Exeter,  owner. 

Bihliographji :  Report  XV,  p.  927. 

Duncan  Magnesite  Mine.  Magnesite  veins  outcrop  on  the  Duncan 
ranch,  in  Sees.  25  and  30,  T.  21  S.,  R.  28  and  29  E.,  on  the  South  Fork 
of  Tule  River,  6  miles  east  of  Porterville.  A  spur  of  the  Southern 
Pacific  branch  line  from  Porterville  reaches  within  a  quarter  of  a 
mile  of  the  property,  which  lies  just  north  of  that  of  the  Hawley 


MAGNESITE    IN    CALIFORNIA.  109 

Pulp  and  Paper  Company,  which  company  also  owns  the  niineral 
rights  on  48  acres  of  the  Duncan  ranch.  The  Duncan  deposits  were 
one  time  leased  by  11.  L.  Doyle  hut  the  lease  allowed  to  expiiv.  The 
California  Maynesite  Company  also  had  a  lease.  Some  ore  was 
shipped  during  the  war,  hut  the  i)roperty  has  been  idle  since  Owned 
by  Claude  Duncan  and  ]\Irs.  JMatilda  Duncan,  Success,  ( 'alifornia. 

Bibliography :  Cal.  State  Min.  Bur.,  Report  on  mines  and  mineral 
resources  of  Tulare  Co.,  December,  1916;  also  Report  XV,  p.  927. 

Fairview  Magnesite  Mines.  The  Fairview,  Fairview  No.  1,  and 
Last  Chance  claims  comprise  this  property  which  is  situated  in  Sec. 
30,  T.  20  S.,  R,  28  E.,  M.  D.  M.  The  locality  is  6  miles  or  more 
southeast  of  Lindsay,  the  nearest  town,  but  not  over  four  miles  from 
the  post  office  of  Strathmore.  On  the  west  slope  of  a  hill,  at  an  eleva- 
tion of  950  feet,  a  crosscut  was  driven  to  cut  a  12-inch  vein  striking 
east  and  dipping  north.  On  the  east  slope  of  the  same  hill  a  number 
of  magnesite  veins  outcrop  and  these  were  developed  by  open  cuts 
and  tunnels.  Owners,  R.  R.  Gilbert  and  W.  F.  Finley  of  Strathmore. 
Idle. 

Bibliogvaphy :  Cal.  State  Min.  Bur.,  Report  on  mines  and  mineral 
resources  of  Tulare  Co.,  December,  1916 ;  also  Report  XV,  p.  928. 

Gill  Ranch  Deposits  (California  Magnesite  Co.,  Tulare  Mining  Co., 
and  Sierra  Magnesite  Co.  leases).  The  Lee  Gill  ranch  covers  an 
extensive  acreage  northeast  of  Porterville.  IMagnesite  deposits  occur 
at  several  places  on  this  ranch,  in  the  trend  of  the  magnesite  belt 
north  and  northwesterly  from  the  mines  on  Porterville  Hill  (Harker 
property) . 

At  one  time  (about  1913-1914),  the  California  Magnesite  Company 
had  leases  on  part  of  the  property  and  operated  three  camps :  one, 
('Camp  4')  on  a  series  of  veins  5  miles  east  of  Strathmore,  and  two, 
C  Camps  2  and  3')  in  Sec.  18,  T.  21  S.,  R.  28  E.,  northeast  of  Porter- 
ville. At  'Camp  4'  on  one  place  a  N.-S.  vein  of  12  inches  to  2 
feet  in  width  was  stoped  from  an  adit  to  the  surface  40  feet  up,  and 
drifted  on  for  150  feet.  A  12-inch  vein  running  N.  30°  W.,  dipping 
NE.  intersects  the  N.-S.  vein  in  the  adit.  There  are  at  least  three 
other  series  of  veins,  on  some  of  which  work  has  been  done.  At 
'Camps  2  and  3',  a  number  of  magnesite  veins  occur  in  brown  ser- 
pentinized  peridotite,  on  the  west  slope  of  a  range  of  foothills  which 
lie  west  of  Frazier  Valley.  There  are  two  general  systems  of  parallel 
veins:  one  strikes  N.  45°  W.,  and  the  other  N.  10°  W.,  the  width 
varying  from  1  foot  to  2  feet.  On  the  west  slope  of  the  hill,  two 
crosscut  adits  were  driven  east,  cutting  the  N.  10°  W.  vein  which 
dips  50°  W. 

The  Tulare  Mining  Company  had  a  lease  on  a  magnesit(>-bearing 
area  in  the  N.|  of  Sec.  7,  T.  21  S.,  R.  28  E.,  northeast  of  Porter- 
ville Hill.  The  ground  has  a  rolling,  hilly  surface  bare  of  timber. 
Water  has  to  be  hauled  to  the  workings,  which  lie  at  an  elevation 
of  1140  feet  above  sea-level.  A  number  of  tunnels  have  been  driven 
on  these  veins  and  considerable  ore  shipped,  crude.  The  veins 
ranged  from  6  inches  to  20  inches  in  width.  One  vein,  striking  N. 
40°  W.  and  dipping  45°  SE.  was  opened  uj)  for  600  feet  along  the 
surface  by  open  cuts;  and  an  adit  drift  at  its  south  end  showed  20 


110  CALIFORNIA    STATE    MINING   BUREAU. 

inches  of  first-class  ore.  Mining  was  ])y  liand  drilling,  and  for  a  time 
a  daily  production  of  15  tons  was  maintained,  with  15  men  employed. 
The  work  was  done  by  contract  on  a  tonnage  basis.  Zante,  a  station 
on  the  Southern  Pacific,  Avas  the  shipping  point. 

The  Sierra  Magnesite  Company  now  has  a  lease  covering  all  of  the 
magnesite  deposits  on  the  Gill  ranch  holdings. 

Bihliographu:  Reports  XV,  p.  926;  XVIIT,  p.  531. 

Hamilton  Ranch  Deposit.  There  has  been  some  work  done  by 
leasers  on  the  J.  C.  Hamilton  ranch  in  Sec.  22,  T.  18  S.,  R.  27  E.,  on 
a  hill  running  easterly  in  the  Yokohl  Valley.  A  crosscut  adit  was 
driven  north  on  the  south  slope  of  the  hill  to  cut  a  series  of  N.  20° 
W.  veins  of  magnesite  that  outcrop  strongly  on  top  of  the  hill.  The 
brown  serpentinized  peridotite  is  intersected  by  a  network  of  small 
veins  ranging  from  6  inches  to  1  foot  wide. 

Bibliograph)/ :  Report  XV.  p.  928. 


Photo  No.  4  8 — View  northward  showing  blanket  veins  being  worked  on  the 
property  of  the  Porterville  Magnesite  Company,  in  1917.  Plioto  by 
C.  A.   Waring. 

Harker  Mine  (Porterville  Magnesite  Company).  The  magnesite 
deposits  on  the  Harker  property,  operated  for  several  years  (1915- 
1920)  by  the  Porterville  JMagnesite  Company  of  San  Francisco,  were 
described  by  Hess  ^  in  1908 ;  but  Avere  first  noted  by  Blake  -  in  1853. 

The  deposit  was  worked  continuously,  but  in  a  comparatively 
superficial  way  from  1901  to  1909  by  the  Willamette  Pulp  and  Paper 
Company,  who  ceased  mining  after  the  upper  ]iortion  of  the  largest 
vein  had  been  worked  out.  The  Harker  property  was  later  acquired 
by  the  Porterville  ]\Iagnesite  Company,  who  recognized  its  possibil- 
ities and  developed  it  to  such  an  extent  that  that  company  for  a 
time  enjoyed  the  distinction  of  being  the  largest  producer  of  magne- 

1  Hess,  F.  L.,  Tile  magnesite  deposits  of  California :  U.  S.  Geol.  Surv.,  Bull.  355, 
pp.  40-46,  1908. 

-Blake,  W.  P.,  ItineraiT.  or  notes,  etc :  Report  of  explorations  in  California,  for 
railroad  routes  to  connect  with  the  routes  near  the  35th  and  32d  parallels  of  north 
latitude,  Washington,   1856,  p.   2S. 


MAGNESITE   IN    CATJFORNIA.  111. 

silt'  not  alone  in  the  I'ortci-villc  district  and  Tulare  ('ount\',  hut  in  the 
-.t;!*e  as  well. 

The  rounded  foothills  wliicii  contain  the  mineral  form  a  jiortion 
of  ()40  acres  owned  by  ]\Irs.  liarn.urover  (widow  of  ('has.  S.  Ilarker), 
of  which  ;M)0  aei-es  are  magnesite  hearing'.  The  entire  property 
was  leased,  with  option  to  buy.  to  the  Porterville  JMagnesite  Company. 
Title  was  not  transferred,  however,  and  the  property  reverted  to  the 
Ilarker  estate,  after  the  elose  of  the  war-period  activity.  From 
October,  1920,  to  January  1,  1928,  it  was  operated  under  lease  by  the 
Sierra  ]\Iagnesite  Company,  the  ore  being  calcined  in  their  furnaces 
at  PorterviUe.  Since  the  summer  of  1923,  the  mine  and  calcining 
plant  have  been  under  lease  to  Iloff  &  Marker,  operating  under  the 
corporate  name  of  California  .Magnesia  Company,  K.  W.  Ilarker, 
i-esident  manager,  540  Murrav  Ave.,  Porterville. 

The  holdings  are  in  Sec.  17,  T.  21  N.,  R.  28  E'.,  M.  D.  M.,  about  4 
miles  northeast  of  Porterville,  the  nearest  railroad  point.  The  work- 
ings are  at  an  elevation  of  from  1200'  to  1500'.  There  is  no  timber 
on  the  property  and  the  water  used  is  hauled  from  Porterville  in 
tank  trucks  to  a  12,000-gallon  storage  tank  at  the  plant. 

l^p  to  and  including  the  greater  part  of  1916,  the  Porterville  com- 
|)any  produced  only  crude  or  raw  magnesite,  but  in  June,  1910,  a 
small  rotary  kiln  was  installed.  This  was  later  supplemented  by  a 
second  and  nuich  larger  one.  The  total  production,  of  both  crude 
and  calcined,  for  1916  was  the  e(|uivalent  of  21,500  tons  of  crude. 
This  figure  was  exceeded  in  1917.  The  principal  deposits  are  in  two 
large  rounded  hills,  where  the  magnesite  forms,  in  part,  a  stock  work 
of  veins  in  brown  serpentinized  peridotite,  resembling  a  bedded  struc- 
ture; the  veins  varying  in  size  from  a  fraction  of  an  inch  to  ten  feet 
in  width. 

The  ore  was  mined  l)y  means  of  open  cuts,  quarrying,  tunnelling, 
and  stoping,  largely  under  contract  on  a  per  ton  basis,  the  company 
furnishing  the  contractors  with  air  drills.  The  average  price  was 
^4.75  per  ton  for  ore  delivered  to  an  accessible  road  for  hauling. 
The  prevailing  wages  paid  in  l!)17  by  contractors  were: 

Machine  men $3.50  — $4.00  per  day 

-Miners 3.00 —    3.2-5   per  day 

Mmkers     2.75  per  day 

In  ^Vugust  1917,  225  men  were  working  in  the  mine  and  the  daily 
output  was  from  250  to  300  tons. 

p]lectric  power  drives  the  air  compressor,  and  the  rotary  kiln.  The 
calcining  equipment  includes  a  7|' x  125'  rotary  kiln  having  a  capac- 
ity of  65  tons  of  calcined  matei-ial  per  day,  and  an  upright  kiln  of 
10  to  15  tons  per  day  capacity.  There  is  also  a  small  ci'usjiing  j)laiit, 
the  e(|uii)ment  of  which  incdudes  a  hammei'-mill  and  a  bulir  mill, 
Ihoiiiih  these  are  otdy  occasionally  used,  most  of  the  product  being 
shipped  unground. 

There  is  a  chain  elevator  to  cari-y  the  hot  ealcined  material  from 
the  kilns  to  a  50' x  120'  cement  cooling  floor.  Steam  for  the  oil 
Itui'iiers  is  furnished  by  a  30  h.  j).  hoi-izontal  boiler,  supplemented 
l)y  a  15  h.  p.  upright  used  as  a  relay.  The  boilers  are  fitted  with 
injectors  but  a  rcday  feed-water  i)unq)  is  connected  to  both  for 
emergency  use.    A  corrugated  iron  building  encloses  the  entire  plant. 


112 


CALIFORNIA    STATE    MINING    BUREAU. 


MAQNESITE   IN    CALIFORNIA.  113 

Fuel  oil  is  obtained  from  the  Coalinga  district.  It  is  emptied 
from  the  railroad  tank  ears  into  a  1000-gallon  reservoir  at  the  siding 
in  Porterville  and  then  pumped  to  two  5000  gal.  tanks  elevated 
10  feet.  Auto  trucks  haul  it  from  there  to  a  20,000-gal.  storage 
tank  at  the  plant.  The  daily  consumption  was  from  5000  to  5500 
gals.,  when  two  rotary  kilns  were  operated  by  the  Porterville 
Company. 

The  Porterville  Company  maintained  an  ore  storage  yard  of  12,000 
tons  capacity  where  the  raw  magnesite  was  mixed  to  make  a  standard 
product  carrying  not  over  3%  lime  and  4%  silica.  The  raw  ore 
ordinarily  averages  2%  CaO'  and  3%  SiO,,  while,  after  calcining, 
the  product  contains  5%  CaO  and  7%  SiOa-  The  larger  kiln  was 
used  to  run  a  lower-grade  ore  carrying  as  high  as  8%  SiOg  and  5% 
CaO.  Though  during  the  war  a  large  part  of  the  product  was  util- 
ized for  refractories,  all  of  the  present  output  of  the  mine  is  used 
in  the  plastic  trade. 

The  freight  rate  to  Chicago  (Class  C  District)  in  April,  1917, 
was  $10  per  ton;  to  Pittsburg  (Class  B  District)  $11.50;  and  to 
New  York  (Class  A  District)  $12.50  per  ton.  The  minimum  car- 
load is  40  tons,  while  average  cars  carry  50  tons  of  crude  or  4() 
tons  of  calcined. 

Mine  Development  and  Geology. 

These  deposits  are  in  the  outer  range  of  foothills,  in  Sec.  17,  T. 
21  S.,  R.  28  E.,  about  4  miles  northeast  of  Porterville.  The  follow- 
ing description  is  abstracted  largely  from  the  reports  of  Hess  ^  and 
Tucker,-  with  observations  by  the  present  writer  covering  the  later 
developments.  The  magnesite  veins  stand  out  prominently  on  two 
rounded  hills,  locally  referred  to  as  'Porterville  PTill.'  One  of  the 
hills,  which  will  be  referred  to  as  the  northern  hill,  runs  a  little 
cast  of  north,  and  the  other,  which  will  be  referred  to  as  the  eastern 
liill,  about  X.  60°  E.  At  their  junction  is  a  saddle  about  300  feet 
below  the  summits.  The  orebodies  on  these  two  have  quite  distinct 
ciiaracteristics.  The  veins  occur  in  a  brown  serpentinized  peridotite 
having  an  apparent  ))edded  structure.  The  serpentine  forms  part 
of  a  metamorphic  complex  consisting  of  a  small  amount  of  fine- 
grained quartzite,  amphibolite  schist,  serpentine,  and  other  magne- 
sian  rocks,  some  of  which  are  talcose  and  mica-bearing.  The  rocks 
liave  a  general  northerly  strike,  with  a  rather  high  (60°)  easterly  dip. 
They  are  cut  off  by  a  granitic  mass  on  the  south,  a  few  hundred 
feet  from  the  deposits.  Several  granitic  dikes  cut  the  serpentine  and 
other  rocks,  but  do  not  cut  the  magnesite  veins,  though  basic 
(likes  (amphibolites)  of  several  varieties  cut  l)oth  country  rock  and 
the  veins.  The  veins  are  here  and  there  squeezed  to  a  schist.  Fault- 
ing is  common  but  does  not  divide  the  serpentine  into  the  small 
irregular  blocks  which  result  in  the  serpentines  of  the  Coast  Range 
and  many  others,  from  tlie  swelling  of  the  rock  as  it  changes  its 
chemical  and  mineralogieal  form.  However,  movement  is  evident 
and  the  magnesite  is  invariably  crushed  in  the  larger  veins. 

•  He.ss,  F.  L.,  The  magnesite  deposits  of  California;  U.  S.  Geol.  Surv.,  Bull.  355, 
pp.    40-46.    1908. 

-  Tiirker.  W.  B.,  Mines  and  mineral  resources  of  Tulare  County ;  Cal.  State  Min 
Bur.,    Report  XV,  pp.    D.-^l-OSS,    lOlfi. 

8— :59SI)2 


114 


CALIFORNIA    STATE    MINING   BUREAU. 


?  ^ 


MAGNESITE    IN    CALIFORNIA.  115 

To  the  east  of  the  hill,  there  is  a  tunnel  at  an  elevation  of  1450 
feet,  in  which  a  vein  8  feet  wide  of  tufa-like  ma^nesite  was  encoun- 
tered. In  this  material  there  had  been  re-formed  normal  magnesite 
which  was  worked.  These  re-formed  veins  follow  no  well-defined 
system.  They  occur  at  such  points  Avhere  the  conditions  were  favor- 
able. The  tunnel  mentioned  is  located  near  a  granite  intrusion  on 
the  eastern  portion  of  the  projx'rty,  and  therefore  the  veins  probably 
lack  continuity. 

]\Iagnesite  veins  in  the  western  area  :  On  the  south  of  the  western 
(or  'northern')  hill,  a  main  gash  vein  has  been  explored  by  a  series 
of  tunnels  at  different  elevations,  the  main  or  lower  tunnel  being 
nearly  1000  feet  long.  This  vein  ranges  in  thickness  from  2'  to  8', 
and  strikes  N.  45°  W.,  dipping  65°  to  70°  NE.  An  amphibolite  dike 
2'  to  3'  thick  has  been  intruded  in  the  serpentine  near  the  vein  and 
follows  it  a  short  distance.  About  lOO  feet  from  the  southeast  out- 
crop of  the  vein  it  is  joined  by  another  vein  of  about  the  same  thick- 
ness, which  has  a  strike  of  N.  10°  W.  These  Veins  have  been  open- 
cut  and  stoped  extensively.  An  interesting  characteristic  of  the 
magnesite  veins  is  noticed  on  this  side  of  the  hill,  and  that  is  that 
they  are  thicker  underground  than  at  the  outcrop,  and  they  widen 
out  to  an  extent  not  anticipated  by  the  thickness  of  the  croppings; 
also  that  intersecting  veins  occur  underground  whose  presence  is 
not  at  all  indicated  by  any  surface  croppings.  These  interesting 
veins  are  usually  smaller  than  the  main  veins,  occur  at  closer  inter- 
vals, and  in  some  cases  occur  so  frequently  as  to  form  a  stockwork 
of  veins. 

Except  for  the  'blanket'  veins  which  are  the  characteristic  feature 
of  the  upper  part  of  the  northern  hill,  and  which  are  described  in  a 
succeeding  i)aragraph,  most  of  the  veins  stand  at  quite  a  steep  angle 
(up  to  70°).  The  photographs  reproduced  herewith  reveal  their 
distinctiveness.  At  the  top  of  the  hill  on  the  Avestern  slope  there  is 
a  large  area  containing  magnesite  veins  from  which  considerable 
ore  has  been  taken. 

To  the  north,  near  the  top  of  the  hill,  the  more  important  veins 
(two  in  particular)  are  tiat-lying,  or  nearly  horizontal,  'blanket' 
veins.  The  exposures  were  easily  traceable  on  the  surface.  In  this 
area  above  elevations  of  1550  feet  on  the  north  end,  three  distinct 
veins  dipping  12°  S.  have  been  mined,  and  between  elevations  1550' 
and  1500'  there  is  a  very  prominent  vein  parallel  to  the  others. 
The  largest  of  these  veins  is  practically  horizontal  in  the  middle  i)art 
and  somewhat  uplifted  at  lioth  ends — north  and  south.  It  extends 
through  the  hill,  a  distance  of  362  feet,  somewhat  longer  than  broad, 
and  from  2'  to  4'  thick.  A  basic  dike  flattens  and  spreads  under 
a  large  part  of  the  vein  in  a  thin  sheet  1'  to  2'  thick ;  then,  breaking 
through,  it  overlies  the  remainder  of  the  vein.  Magnesite  veinlets 
fill  cracks  in  the  dike,  but  the  mass  of  the  vein  is  cut  by  it.  There 
is  nothing  to  show  that  the  vein  has  been  tilted  from  a  more  upright 
j)osition  to  its  present  place.  It  was  evidently  formed  as  it  lies, 
flat  and  cutting  across  the  vertical  structure  of  the  serpentine. 

"This  is  accounted  for  by  supposing  that  there  was  a  slow  movement  in  the  rocl<s 
along  this  plane  at  the  time  of  the  vein'.s  deposition,  the  magnesite  filling  uneven 
open  spaces  along  the   lun-izont.il    fault,   and   that   vvlien   there   was   anothi-r   movement 


116 


CALIFORNIA    STATE    MINING    BUREAU. 


these  deposits  held  the  mass  apart  and  made  room  for  contiguous  deposits.  Tiie 
crushed  condition  of  the  whole  mass  and  the  presence  of  inclusions  of  serpentine  in 
lines  approximately  parallel  to  the  sides  of  the  vein  give  this  hypotliesis  some  color."  ' 

Intersecting  veins  more  or  less  vertical  occnr  over  this  entire 
area,  from  which  eonsideral)le  ore  has  been  extracted.  The  work- 
ings on  the  blanket  veins  consist  of  a  series  of  tnnnels,  from  which 
the  magnesite  was  mined  by  a  s.vstem  similar  to  that  practiced  in 
Hat  coal  seams.  The  waste  broken  from  stripping  the  vein  was 
nsed  to  snpport  the  roof.  A  main  haulage  way  Avas  maintained,  with 
a  series  of  laterals  run  off  at  convenient  intervals.  These  tunnels 
extend  all  the  way  through  the  hill  on  the  horizontal  veins ;  but 
practically  all  the  available  ore  there  has  now  been  mined  out. 

To  the  north  of  this  area,  on  the  north  slope  of  the  hill,  and  at 
lower  elevations  numerous  outcrops  of  magnesite  have  been  devel- 


Photo   No.    51— Calcining   plant   at   Harker    Mine    (Porterville    Magnesite    Company), 
near  Porterville,    Tulare    County. 

oped  bv  means  of  adit-drifts  and  open  cuts.  These  veins  vary  from 
2'  to  10'  thick,  with  blanket  veins  from  1^'  to  3'  thick,  the  magnesite 
from  them  being  of  high  quality.  On  one  of  the  strongest  of  the 
steep  veins,  the  adit  was  driven  several  hundred  feet  at  elevation 
10.50  feet,  showing  the  strike  to  be  S.  40°  E.,  with  dip  50°  SW.  and 
a  width  of  2'  to  4'.  This  vein  has  been  stoped  through  to  the  surface, 
as  have  several  others,  since.  The  walls  show  a  very  strong  move- 
ment with  a  drag  to  the  southeast.  On  one  of  these  veins  (named 
the  'Bartlett')  developments  have  extended  down  to  a  depth  of 
500  feet  below  the  outcrop.  When  visited  in  November,  1923,  a 
winze  was  being  sunk  and  a  hoist  installed,  as  a  lower  adit  could 
not  be  driven  because  of  being  near  the  north  end-line  adjoining 
the  ground  of  the  Sierra  Company. 

'  Hess,  P.  L.,   Op.  cit.,  p.  43. 


MAGNESITE   IN    CALIFORNIA.  117 

On  the  South  or  'eastern'  hill  all  of  the  veins  are  steep-dipping 
and  characteristically  of  the  'gash'  type;  while  there  are  both 
blanket  and  steep  veins  in  the  'north'  hill.  The  l)nlk  of  the  produc- 
tion on  this  property  has  come  from  the  north  hill,  and  present  opera- 
tions are  largely  confined  to  that  end.  The  mining  of  the  ore  has 
been  done  (and  still  continues)  principally  on  a  leasing  or  a  con- 
tract basis,  the  company  furnishing  compressed  air  and  tools.  In 
1917,  at  least  nine  such  leases  were  listed.  In  part,  the  ore  has 
been  trammed  around  the  hill  to  chutes  leading  to  the  furnace  plant, 
and  in  part  hauled  by  motor  trucks.  At  present,  the  latter  is  used, 
solely. 

Furnace    Equipment. 

AVhen  visited  in  Noveml)er,  192:3.  the  rotary  kiln  Avas  not  in  use, 
the  present  lessees  confining  theii-  work  to  the  vertical  kiln  of  15  tons- 
calcined  daily  capacity.  The  product  is  shipped  for  plastic  purposes. 
The  grinding  eciuipment,  consisting  of  a  hammer  mill  and  a  buhr  mill 
were  not  being  utilized  at  the  time,  the  calcined  material  being  sent 
out  entirely  in  the  lump  or  grain  form. 

Bibliogniphy:  Cal.  State  Min.  Bur.,  Reports  XY,  pp.  931-935; 
XVIII,  p.  531 ;  XX.  p.  30 ;  Bull.  38,  pp.  333-334.  U.  S.  Geol. 
Surv..  Bull.  355,  pp.  40-46;  Bull.  540,  p.  509. 

Hawley  Pulp  and  Paper  Company.  This  company  owns  the  min- 
eral rights  on  43  acres  of  the  INIatilda  and  Claude  Duncan  property, 
in  the  Success  mining  district.  These  holdings  in  the  W.l  of  Sec.  30, 
T.  21  S.,  R.  29  E.,  M.  D.  M.,  adjoin  the  old  Tulare  Mine,  and  are 
reached  by  a  spur  of  the  Southern  Pacific  branch  from  Portervill(\ 
Water  is  obtained  from  the  South  Fork  of  Tule  River  which  flows 
through  the  ])roperty.  The  rolling  hills  are  bare  of  timber,  but  a 
few  oaks  grow  near  the  river. 

A  considerable  amount  of  work  has  l)een  done,  hand  labor  having 
been  used. 

For  several  years  the  product  went  first  to  Berkeley  where  it  was 
calcined,  the  Pure  Carbonic  Company  taking  the  gas  and  shipping 
the  calcined  magnesite  to  the  Ilawley  Company's  mill  at  Oregon 
City,  Oregon,  where  it  was  iitilized  in  the  maiuifacture  of  bisuli)hit(' 
pulp.  Approximately  1500  tons  of  the  raw  material  had  been  shi})[)(Ml 
up  to  July,  1917,  when  the  property  was  taken  over  by  the  Tulare 
]\Iining  Company.  Later,  it  was  transferred  to  the  Sierra  Magne- 
site Com|)any  when  that  company  acquired  the  Tulare  Company's 
holdings.  The  lease  on  the  Ilawley  ground  has  since  been  allowed 
to  lapse. 

Two  systems  of  veins  with  steep  dips  have  been  opened  up  and 
several  blanket  veins  cut.  The  ])rincipal  workings  and  the  orebodies 
exposed  are : 

No.  1,  or  lower  tunnel.  This  crosscuts  a  vein  striking  N.  55°  AV. 
and  dipping  63°  NE.    The  vein  mined  was  from  Pi'"  to  30"  wide. 

No.  2  tunnel  is  (m  the  same  level  as  the  main  tunnel  of  the  Tulare 
IVIining  ('ompany's  property  adjoining.  A  four-foot  vein  strikes  N. 
65°  E.  and  dips  flat  into  the  hill.  It  was  cut  by  a  drift  into  the  hill 
from  the  main  tunnel.     The  main  ledge  from  the  Bartlett  property 


118  CALIFORNIA    STATE    MINING   BUREAU. 


I 


strikes  N.  45°  W.  into  the  top  of  the  tunnel,  and  is  from  1'  to  5' 
wide.  It  is  exposed  12"  wide  for  30',  after  which  it  splits  to  the 
south. 

A  tunnel  in  the  guleh  opened  up  a  2'  to  3'  vein  striking  N.  40°  W. 
and  dipping  45°  NE.  The  vein  was  exposed  for  about  120'  in  the 
180-foot  tunnel.  A  tunnel  on  the  hill  at  an  elevation  of  1030  feet, 
exposed  a  2-foot  vein  striking  N.  10°  E.  for  a  distance  of  75  feet 
along  the  roof.  A  branch  vein  showing  for  20  feet  and  6  inches 
wide  was  followed  for  40  feet  after  Avhieh  it  scattered. 

An  outcrop  on  top  of  the  hill  at  an  elevation  of  1100  feet  shows 
a  3-foot  vein,  striking  N.  35°  E.  and  dipping  30°  SW.  A  tunnel 
cutting  this  vein  at  a  lower  level,  showed  it  to  have  a  width  of  18 
inches  for  160  feet  in  the  hanging  wall.     The  ore  is  high  grade. 

The  home  office  of  the  Hawley  Pulp  and  Paper  Company  is  Oregon 
City,  Oregon.    The  property  has  been  idle  the  past  3  or  4  years. 

BihliograpJiu :  Cal.  State  Min.  Bur.,  Reports  XV,  p.  928;  XVI 11, 
p.  531. 

Hayden  Magnesite  mine.  The  deposit  is  on  Hayden  Hill,  the 
property  of  H.  T.  Hayden.  Dinuba.  Dinuba  is  the  nearest  town 
but  shipping  facilities  are  provided  at  Sultana,  a  point  nearer  to  the 
mine  and  all  shipments  Avent  forward  from  there.  It  cost  $1  per  ton 
to  haul  from  the  mine  to  Sultana. 

The  deposit  on  Hayden  Hill  consists  principally  of  a  stockwork  of 
magnesite  veins  and  these  apparently  had  been  largely  worked  out 
when  visited  in  1917.  The  mining  was  done  by  contract,  the  owners 
paying  the  contractors  $4  per  ton  for  ore  on  the  dump.  Eight 
men  were  working  by  contract  and  taking  out  about  |  ton  per  day 
each,  b,y  hand  labor,  with  wheelbarrows  and  bar  drills;  the  con- 
tractors furnishing  their  own  powder.  Shipments  of  ore  in  1917 
amounted  to  660  tons  in  March  and  270  tons  in  April,  when  the 
increasing  leanness  of  the  deposit  made  mining  under  the  contract  j 
terms  no  longer  attractive.  ' 

Headberg  Magnesite.  A  stockwork  of  magnesite  veins  in  ser- 
pentine on  the  Headberg  property,  mined  in  the  past  by  quarrying, 
has  now  remained  unworked  for  some  time.  The  deposit  is  situated 
44^  miles  east  of  Lindsav  in  the  foothills  on  the  east  side  of  Round 
Valley  in  Sec.  11,  T.  20  S.,  R.  27  E".,  M.  D.  M.  John  Headberg, 
Lindsay,  owner. 

Bibliographii :  Cal.  State  Min.  Bur.,  Report  on  mines  and  mineral 
resources  of  Tulare  Co..  December,  1916;  also  Report  XV,  p.  936. 

Joyner  Bros,  (see  also  Merryman  Mine).  This  property  adjoins 
the  Dumont  Mine,  5  miles  east  of  Exeter.  Some  shipments  were 
made  during  the  war  period,  but  there  has  been  no  work  done  there 
lately. 

Lindsay   Magnesite    Company    (see   Sierra   Magnesite    Company). 

This  company  during  1916-1918  was  the  largest  producer  in  the 
county  without  a  calcining  plant.  The  property  was  one  time  owned 
by  Minford  Y.  Smith  of  San  Francisco,  who  sold  it  to  S.  R.  Coghlan, 
the  Lindsay  Company  purchasing  from  Coghlan  in  March,  1916,  and 


ma(;nerite  IX  California.  Ill) 

later  selliiiji'  to   tlie   Tularo   ^Mining'   Company   whose   mine   adjoined 
on  the  north. 

Bibliography.  Cal.  State  ]\Iin.  Bur.,  Report  XV,  pp.  929-931. 

McKiernan  Mine.  ().  McKiernan  of  }*orterville  owns  ground  on 
the  west  side  of  tlie  Lindsay  mine  of  the  Sierra  ]\IaKiiesite  Company. 
Me  has  an  open-cut  quarry  in  w^hich  magnesite  is  broken  from  a 
series  of  4"  to  5"  stringers.  The  ore  is  somewhat  crumbly.  It  is 
sold  crude  to  the  Sierra  Company. 

Mentz  Property  (Ravalli  lease).  In  1917,  Joe  Ravalli  did  some 
development  and  shipped  some  ore  from  the  property  of  Wilko  Mentz, 
undei"  a  lease  on  KJO  acres  comprising  the  SP].]  of  See.  28.  T.  22  S., 
R.  2S  E..  M.  1).  i\l.,  northeast  of  Terra  Bella. 

Tile  magnesite  is  found  in  serpentine,  and  there  was  a  total  of 
<).")  tons  produced  in  two  months  by  hand  labor  in  open  cuts.  There 
are  several  veins,  vai-ying  from  (i  inches  to  2  feet  in  width;  and  the 
ground  apparentl.v  has  possibilities  with  depth. 

There  were  two  other  leases,  south  and  soutiiwest,  respectively, 
from  the  Ravalli  lease,  on  which  some  work  was  done  about  191H 
oi-  1917,  and  a  small  amount  of  magnesite  shii)ped.    Idle. 

Merryman  Magnesite  mine.  The  mine  is  owned  by  the  ^lerryman 
P^'uit  &  Land  Companv  and  is  situated  on  their  property  in  the  N.? 
of  Sec.  7.  T.  19  S.,  R.  27  E.,  :\I.  D.  M.  Exeter  on  the  Southern  Pacific 
Railroad  is  2  miles  to  the  Avest  and  the  Visalia  Electric  Railway 
passes  Avithin  a  mile  of  the  deposit.  The  magnesite  is  on  the  rounded 
southwest  spur  of  Rocky  Hill,  Avhere  it  occurs  as  seams  and  veins 
in  serpentine  about  2000  feet  from  a  granite  contact. 

The  ore  w^as  mined  by  contract  on  a  basis  of  $3.50  per  ton,  and 
an  average  of  10  men  were  employed.  The  mine  is  reported  to  have 
l)roduced  2500  tons  in  1916,  and  a  somewhat  larger  amount  in  1917. 

The  nu\in  workings,  from  which  the  output  thus  far  has  come,  are 
on  the  west  slope  of  the  hill.  On  the  south  slope,  the  vein  is  open-cut 
2'  wide  by  50'  long.  It  strikes  N.  40°  W.  and  dips  45°  away  from 
the  granite.    A  3-foot  blanket  vein  strikes  north  and  dips  west. 

Open  cuts  on  the  north  slope  of  the  saddle  in  a  rocky  point  just 
north  of  the  creek,  developed  a  12-inch  vein  opened  20'  deep  and  50' 
in  length,  from  which  ore  has  been  mined.  A  cut  50'  lower  in  eleva- 
tion, shows  the  same  vein  but  it  is  nai-rowei-.  Other  work  carried 
on  along  the  southeast  slope  of  the  hill  northeast  of  the  main  w^ork- 
ings  exposed  a  6'  to  8'  vein  whirh  had  been  abandoned.  The  ore 
carries  but  2'/,  CaO  and  29v  SiO,.  A  lowei-  working  shows  a  2-foot 
vein  of  magnesite  striking  N.  and  dipping  40°  W.,  opened  by  a 
20-foot  tuiniel,  fi'  high.  This  vein  is  on  the  adjoining  80-acre  property 
of  C.  W.  Ostrander  of  Hollywood. 

The  Merryman  Fruit  and  Land  Company's  mine  was  leased  to  A. 
Joyner,  Exeter,  on  a  royalt.v  of  10^^  on  the  gr-oss  value  of  the  ore, 
whii'h  was  shii)|)ed  to  the  ])lant  of  the  Amei-jcan  Refractories  Com- 
pany at  i'orterville,  foi'  calcining,     idle  for  several  years  past. 

Bibliography:  Cal.  State  Min.  Bur.,  Report  on  mines  and  mineral 
resources  of  Tulare  Co.,  December.  1916;  also  Report  XY.  p.  931 
U.  S.  Geol.  Surv.,  Bull.  355,  p.  49. 


120 


CALIFORNIA    STATE    MINING   BUREAU. 


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MAGNESITE   IN    CALIFORNIA. 


121 


Mitchell  Magnesite.  There  is  a  small  deposit  of  inagiiesite  at 
Rocky  Hill,  2  miles  east  of  Exeter,  on  the  Mitchell  property,  which 
produced  for  two  months  during  1916.  Four  men  were  employed 
and  the  owner,  H.  D.  Lester  of  Exeter,  reports  that  150  tons  Avas 
mined  and  sold.  The  mine  did  not  pay  and  AA'ork  was  stopped. 


Photo  No.   5o — V'erlioal  kilns  of  tlie  Tulare  Mining  Company 
(now   Sierra   Magnesite),   at  Magnesite  Station,   Tulare 
County. 

Montgomery  Property  (Davis  Lease).  Magne.site  to  the  amount 
of  1:^02  tons  is  r('i)()it<'(l  tt»  liave  l)e('n  produced  during  191fi  from  the 
property  of  P.  •).  S.  .Moiitgomeiy,  of  Lindsay,  undei-  a  lease.  Tlie 
h'ssee  is  said  to  have  received  from  $9  to  $11  per  ton  for  the  magne- 
site and  to  have  paid  the  owner  $1.25  per  ton  royalty.     Idle. 

Bibliographij :  Report  XV.  p.  026. 


122 


CAIilFORNIA    STATE    MINING    BUREAU 


MAGNESITE    IN    CALIFORNIA.  123 

Oakland  Magnesite  Company.  Address,  Realty  Syndicate  Bldg., 
Oakland,  Cal.,  C.  P.  Miirdock,  President.  This  company  controlled, 
by  lease,  nearly  a  thousand  acres  in  two  localities.  On  the  basis  of 
•1^0.75  per  ton  rovaltv  a  lease  is  held  on  the  mineral  rip'hts  of  480 
acres  of  the  propei-ty  of  J.  AV.  Lanoley  in  Sec.  21,  T.  22  S..  R.  28  E., 
M.  D.  ]\I.,  8  miles  by  road  southeast  of  Porterville;  l)ut  no  work  has 
been  done  recently  on  this  property.  Another  50()-acre  lease  included 
a  strip  200  feet  Avide  sul)-leased  from  the  Porterville  ^Magnesite 
Company  on  a  basis  of  .^1.50  per  ton  royalty,  and  the  balance  on 
property  of  Lee  Gill,  at  $1.25  per  ton.  The  tAvo  latter  holdings 
adjoin  and  lie  in  Sees.  7  and  8,  T.  21  S..  R.  28  E..  4  mih^s  northeast 
of  Porterville.  The  physical  character  of  the  lands  ami  the  mineral- 
ization do  not  materially  dift'er  in  the  tAvo  localities.  Poth  leaseholds 
are  in  the  rolling  foothills  and  contain  magnesite  distributed  as  veins 
in  serpentinized  jx'ridotite.  The  second-named  grouj)  Avas  taken 
over  in  1!)20  liy  the  Sierra  Magnesite  Company. 

The  Deer  Creek  and  North  Mine  on  the  Langley  Leasehold  in 
Sec.  21  was  equipped  for  a  creAv  of  20  men.  Over  10,000  tons  was 
shipped  from  here  in  1916-1917.  The  ore  Avas  mined  by  hand 
methods.  8  men  being  employed.  It  sold  for  $7.50  per  ton.  A  vein 
of  bi'OAvn  magnesite  averaging  20  inches  in  Avidth  and  striking  X.  45° 
E.  is  here  cut  by  other  veins,  AA'hite  in  color.  The  broAvn  magnesite 
is  of  good  quality  and  of  an  older  formation  than  the  Avhite  ore.  A 
flat  vein  of  Avhite  magnesite  striking  N.  70°  E.  shoAved  about  1600 
tons  of  probable  ore.  There  is  also  a  considerable  tonnage  in  sight 
on  the  surface. 

Rex  Plaster  Company  (see  Sierra  Magnesite  Co.). 

Sierra  Magnesite  Company  (see  also  Tulare  Mining  Company,  Rex 
Plaster  Company,  Lindsay  Mining  Company,  Oakland  Magnesite 
Company,  Gill  Ranch  Leases).  This  company  Avas  organized  in  1920. 
and  took  over  all  of  the  important  producing  properties  in  the  vicin- 
ity of  Porterville,  Avhich  they  still  retain  Avith  the  exception  of  the 
Harker  Mine  (Porterville  Magnesite  Company)  AA'hich,  hoAvever,  they 
operated  to  the  end  of  1922.  The  Sierra  Company  noAV  OAvns  in  fee 
the  properties  described  in  preceding  reports  of  the  State  ^lineral- 
ogist  ^  under  the  folloAving  names :  Tulare  ^Mining  (Company,  Rex 
Plaster  Company,  Lindsay  Mining  Company,  and  mineral  rights  of 
tbe  Oakland  ^Magnesite  Company  on  80  acres  adjoining  the  Ilarker 
Mine  on  the  north.  This  company  also  has  a  lease  on  the  magnesite 
deposits  on  the  Cill  ranch  adjoining  the  Oakland  ground  on  tlu' 
north.  They  also  had  a  lease  on  the  minei-al  rights  held  by  the 
flaAvley  Pulp  and  Pai)er Company  on  the  Duncan  j)i-operty  at  Success, 
but  it  Avas  alloAved  to  lapse.  The  frst  three  groups  adjoin  and  are 
in  the  Success  district  7  miles  east  of  Porterville.  Tiie  Oakland-Gill 
group  are  on  the  north  of  Porterville  Hill  4  to  5  miles  northeast 
fi-om  the  i-ailroad  station  at  Porterville.  Recent  operations  have  been 
contined  nuiinly  to  the  'Tulare'  grouml,  and  ])ortions  of  the  'Liiulsay' 
and  the  'Gill  Lease'  properties,  the  last-named  being  Avorked  uiulei" 
a  contract  by  Ed  Ci-aniei-.  All  calcining  is  done  in  rotai'y  fui'uaces 
at  their  plant  in   I'oi-lerville   (foi-merly  American   Refractories  Com- 

'  Report  XV,  pp.  919-940,   1917;  Report  XVIII,  pp.  528-535,   1922. 


124  CALIFORNIA    STATE    MINING   BUREAU. 

pany;  also  American  Magnesite  Company,  a  subsidiary  of  Inter- 
national Magnesite  Company).  Ore  from  the  Success  district  is 
brought  in  by  rail  over  the  branch  line  of  the  Southern  Pacific  Com- 
pany, and  from  the  others  by  motor  truck. 

These  various  properties  are  here  described  in  the  order  of  their 
geographical  occurrence  from  south  to  north. 

MINES. 

REX  PLASTER  mine.  This  property  comprises  the  S.^  of  B.i  of 
Sec.  31,  T.  21  S.,  R.  29  E.,  M.  D.  M.,  in  the  Success  district^  Veins  of 
magnesite  occur  in  serpentine  and  peridotite  on  rounded  hills  with 
grass-covered  slopes  but  bare  of  timber.  The  property  lies  at  an 
elevation  of  about  1400  feet,  and  water  is  obtained  from  the  South 
Fork  of  Tule  River.  Most  of  the  veins  are  small  and  were  worked 
largely  through  open-cuts,  by  hand  labor.  One  open-cut  at  1000' 
elevation  showed  an  18-inch  vein,  strike  N.  20°  W.,  dip  85°  SW. ; 
another  at  1400'  a  2-foot  vein,  strike  N.  20  E.,  dip  85°  SE. ;  another, 
150'  southeast  of  preceding,  shows  five  8-inch  to  6-inch  blanket  veins 
dipping  NW.  20°  into  the  hill,  and  which  were  worked  over  a  thick- 
ness of  5  feet;  another  at  200'  southeast  of  preceding,  at  elevation 
of  1310',  a  10-inch  vein,  strike  N.  30  W.,  dip  75°  E.,  also  a  4-inch 
vein  near  by;  also  a  4-foot  blanket  vein  dipping  25°  N.,  overlain  by 
a  hard  rock  carrying  grains  of  chromite.  This  last-named  was  also 
worked  by  open  cut. 

On  the  'Avery  Lease'  in  the  Rex  Plaster  property,  ore  was  devel- 
oped by  means  of  several  tunnels  and  one  x)pen  cut.  In  an  adit  at 
1100'  elevation,  two  8-inch  blanket  veins  were  exposed,  strike  E., 
dip  15°  S. ;  also  a  12-inch  vein  was  worked.  At  1125'  elevation,  an 
adit  follows  a  vein  1'  to  3'  Made  separated  by  6  inches  of  serpentine ; 
and  in  an  adjacent  vein  having  same  strike,  N.  20°  E.  and  dip  75° 
"W.,  ore  is  exposed  1'  in  width,  about  20'  below  the  surface  and  25' 
above  the  last-mentioned  tunnel.  An  open  cut  and  a  drift  farther 
north,  at  elevation  1130'  exposed  a  1'  to  4'  vein  of  first-class  ore, 
with  strike  E.  and  dip  65°  S. 

The  principal  shipments  from  the  Rex  Plaster  property  were 
made  in  1916-1917,  the  ore  being  sent,  crude,  to  the  company's 
calcining  plant  at  Los  Angeles  and  utilized  for  plastic  purposes.  No 
work  has  been  done  since  November  or  December,  1917. 

LINDSAY  MAGNESITE  mine.  These  holdings  comprise  160  acres 
in  the  N.^  of  S.^  of  Sec.  31,  T.  21  S.,  R.  29  K,  M.  D.  M.,  situated 
between  the  'Rex  Plaster'  on  the  south  and  the  'Tulare'  on  the  north. 
During  1916-1917  this  mine  was  one  of  the  most  important  three 
magnesite  operators  of  the  district  and  the  largest  producer  in  Tulare 
County  without  a  calcining  plant,  all  shipments  having  been  made 
crude.  All  work  at  that  time  was  done  by  hand  labor.  The  deposits 
were  mined  partly  on  company  account  and  partly  by  contract.  On 
company  account,  miners  received  .$3  per  day,  muckers  .$2.75,  and 
tool  dressers  .$3.50  to  $4.  There  were  15  miners  employed,  with  a 
total  of  50  men,  including  teamsters,  on  the  payroll.  The  average 
output  was  80  tons  of  magnesite  per  day  or  2000  tons  per  month. 


MAGNESITE    IN    CAIJFORNIA.  125 

The  maguesite  was  opened  up  in  veins  in  serpentinized  peridotite, 
on  a  large  rounded  hill,  the  average  elevation  of  the  earlier  workings 
being  about  1200  feet.  The  following  workings  were  noted  by 
C.  A.  Waring  ^  in  April,  1917 : 


averages  2'  thick.  (C)  Ledge:  two  open  cuts  above,  average  8'  deep  and  expose 
10-inch  veins  for  50'.  (D)  LOWER  KELLEY  tunnel  at  elevation  of  1150'  is  opened 
for  190'  along  a  30-inch  vein  which  has  125'  of  backs  to  the  Kelley  tunnel.  (E) 
KELLEY  tunnel  at  elevation  of  1265'  has  a  250'  ore  shoot  which  averages  2J'  wide. 
(F)  Xo.  3  shoot  is  240'  long  and  w-ill  average  about  3i'  wide.  (G)  No.  4  shoot 
splits  into  two  shoots,  21'  wide,  one  300'  and  one  120'  long.  (H)  Quarry  on  hill 
worked  to  160'  below  surface  where  vein  was  3'  wide;  ore  shoot  was  110'  wide, 
worked  on  two  levels  70'  and  40' ;  and  50'  to  the  surface.  It  lies  north  of  the  Kelley 
shoot  and  has  not  yet  been  developed  deeper.  (I)  No.  1  tunnel  cut  an  ore  shoot 
striking  N.  40°  W.,  and  averaging  28  inches  wide.  Ore  has  been  worked  out  in  the 
three  upper  levels.  The  lower  level  or  that  of  the  tramway  track,  has  been  run 
86.6'  below  to  cut  the  ore  shoot." 

Production  from  this  property  in  1916—1917  totaled  in  excess  of 
38,300  tons.  The  ore  was  trammed  around  the  hill  to  a  chute 
('Adams  Chute')  800  feet  long  (see  Photo  Xo.  52)  connecting  with 
a  spur  track  of  the  Southern  Pacific  from  the  Tulare  Mine  branch. 

AVhen  visited  by  the  writer  in  November,  1923,  a  depth  of  385 
feet  below  the  outcrop  had  been  reached  in  a  winze  sunk  below  'No.  7 
Tunnel'.  This  crosscut  adit  cut  the  orebody  at  868'  in,  from  which 
point  a  drift  had  been  run  150'  N.  On  this  level  the  two  main 
veins  of  the  Lindsay  join.  The  winze  ('No.  43')  was  down  64'  and 
showed  2'  of  pure-white,  high-grade  ore  in  the  bottom.  On  one 
wall  there  was  a  layer  of  a  soft  white  mineral,  which  proved  on 
analysis  in  the  laboratory  of  the  State  Mining  Bureau  to  be  hydro- 
magnesite.  Ore  has  been  stoped  out  above  No.  7  tunnel  to  a  height 
of  140'.  The  present  company  has  a  compressor  plant  at  the  poi-tal 
of  No.  7  to  supply  air  for  drilling. 

TULARE  ^MINING  Comi)any  ground.  Those  holdings  which  wen- 
taken  over  bv  the  Sierra  Companv  in  April,  1921,  comprise  the  X.:', 
of  See.  31,  and  a  portion  of  Sec.  30,  T.  21  S.,  R.  29  E.,  ]\I.  1).  M. 
■-Magnesite'  station  at  the  property  is  on  a  spur  track  southeasterly 
from  Success  Station  on  the  Springville  branch  line  of  the  Southern 
Pacific  railroad  running  up  Tule  River  from  Porterville.  The  eleva- 
tion of  the  plant  near  the  base  of  the  hills  containing  the  deposits  is 
only  700',  but  the  hills  rise  steeply  (see  Photo  Xo.  52)  from  the 
edge  of  the  south  fork  of  Tule  River  to  twice  that  height.  Water 
for  all  needs  is  obtained  from  the  river,  but  timber  is  scarce  through- 
out the  district.  The  portion  of  the  hills  containing  the  magnesite 
veins  is  a  highly  serpentinized  rock  and  the  occurrence  is  typical, 
embracing  both  large  veins  and  a  stockwork  of  small  veins. 

The  Tulare  Company  operated  two  oil-fired,  vertical,  shaft  furnaces 
at  the  mine,  with  a  cement  cooling-floor  and  sacking  i-oom  below 
alongside  the  railroad  track;  but  the  present  company  does  all  of 
its  calcining  in  the  rotary  kilns  at  Porterville.  They  have  a  50-cent 
rate  per  ton  on  the  crude  ore  from  Magnesite  to  Porterville.  The 
old  shaft  kilns  serve  as  storage  bins  in  the  ore-bunker  and   cliute 


Original  manuscript  of  this  bulletin. 


126 


CALIFORNIA    STATE    MINING    BUREAU. 


system.  Jn  1917,  there  were  133  men  employed,  and  the  mine  output 
was  80  tons  of  crude  ore  i)er  day,  from  which  36  tons  of  calcined 
material  was  obtained. 

The  following  workin<is  were  listed  by  Waring  ^  as  being  in  active 
oi)eration  in  April,  1917:  GULCII  TUNNEL  stopV ;  SIMALL  TUN- 
NP:L  400'  west;  HOOPER  TRACT  tunnel;  SOUTH  SUiMMIT  No.  3 
level;  SOUTH  SU:\IMIT  tunnel;  SOUTH  SUMMIT  east  stope ; 
BLANKET  LEDGE;  QUARRY  beloAv  the  blanket  ledge;  NORTH- 
EAST TURNER  stope;  SOUTH  SU.AOIIT  QUARRY  lower  stope;  a 
LOWER  QUARRY  below  South  Summit  ([uarrv;  LEAD  TRAIL 
QUARRY ;  OLD  FLUME  TUNNEL  south  of  kilns ;  TUNNEL  No.  6. 
The  following  table  show^s  the  percentages  of  CaO  and  IMgO  in 
samples  of  ore  from  several  of  the  openings  listed  above: 


Photo 


SiciclvWurk    \tiiis   at    'LoW'-i'    tiiiari-y    on    Sierra    'Standard'    workings. 


Per  cent  Per  cent 

CaO  MgO 

Lower   track    tunnel 7.49  89.0 

South    summit   east   tunnel 3.21  94.0 

Summit    NE.    tunnel 0.00  94.0 

Lower  blanket  quarry 0.00  96.0 

South   summit    quarry 3.85  93.0 

LTpper    track    tunnel    stope ,5.53  SSio 

South   summit   blanket  stope 0.30  97.0 

South   summit   tunnel   stope 1^78  96!o 


The  magnesite  veins  developed  in  these  various  workings  range 
from  mere  seams  up  to  orebodies  which  have  been  stoped  out  to  a 
width  of  38  feet.  The  strike  of  the  steep  veins  varies  between  N. 
80°  E.  and  N.  75°  W.,  with  dips  up  to  80°.  In  some  places,  the  stock- 
work  as  a  whole  has  been  mined.  For  example  in  the  'Lead  Trail' 
quarry  a  face  30'  high  by  40'   Avide  was  worked   carrying   a   stock- 

'  Waring,  C.  A.,  in  original  manuscript  of  this  bulletin. 


MAGNESITE   IN    CALIFORNIA. 


127 


work  of  vt'inlets  varyiji.i;'  tVoiu  (i  inclics  to  2  feet;  and  of  the  total 
material  (juarried  80'/   was  ore  and  TO'/*   waste. 

The  workinjjs  are  too  nuineroiis  and  many  of  them  intersecting?  to 
attempt  a  detailed  description  of  each  of  them.  The  ol)server  and 
the  reader  would  lose  a  proper  prosix'ctive  of  the  wiiole,  in  a  maze 
of  intricate  detail. 

For  convenience  of  reference,  the  present  company  has  divided  the 
workings  in  this  district  into  three  groups:  south,  central,  and  noi-th  ; 


k^§^'  j/^^"^^ , 


-•-■  -'^. ' 


LiiTjl 


Photo  No.  56 — Stockwork  of  veins  in  No.   9  Quarry    ('South  Summit 
Quarry')    at   Sierra   'Standard"    woi-king.s. 

which  they  have  designated  the  'Lindsay,'  'Standard'  or  'Tulare 
South,'  and  the  'Tulare'  (or  'North'),  respectively.  The  'Lindsay' 
comprises  the  territory  of  the  former  Liiulsay  Mining  Company 
described  on  a  preceding  i)age;  while  the  ' Standard'  and  'Tulare" 
cover  the  ground  of  the  old  Tulare  Mining  Company. 

In  the  'central'  hill  or  'Standard'  section,  the  vein  system  is 
essentially  that  of  a  rather  extensive  stockwork.  This  is  vei-y  well 
shown   in  the  two  photogra})hs   (Xos.  ;").">  and  •")(;)    hei-ewitli.     I'nder- 


128 


CALIFORNIA    STATE    MINING    BUREAU. 


MAGNESITE   IN    CALIFORNIA.  129 

ground,  in  some  places  the  flat  veins  widen,  and  in  others  the  verticals 
or  inclined  veins  widen  out  to  workable  orebodies.  It  can  be  readily 
seen  how  such  irregularities  Avould  result  in  an  intricate  maze  of 
intersecting:  workings  underground. 

In  the  'Tulare'  or  north  section,  the  occurence  is  that  of  a  zone 
of  'nodular'  ore  and  irregular  segregations  in  the  serpentine,  being 
a  series  of  discontinuous  or  intermittent  segregations.  This  zone 
has  a  northwest  strike,  with  dip  60°  ±:  E.,  and  is  from  30'  to  90'  wide. 
In  the  earlier  reports  on  this  property  this  zone  is  referred  to  as  a 
'vein.'  Parallel  to  and  west  of  the  nodular  zone,  there  is  a  magne- 
site  'vein'  which  varies  from  a  few  inches  to  4'  in  width,  and  west 
of  this  vein  there  is  what  appears  to  be  an  intrusive  dike. 

The  present  operators  ship  three  grades  of  ore  from  this  'Tulare' 
section:  'Tulare  A,'  'Base  Coat,'  and  'Tulare  Special  Select.'  The  tirst 
two  are  calcined  for  plastic  mixtures,  and  their  compositions  are  given 
in  a  succeeding  paragraph.  The  third  is  shipped,  crude,  to  chemical 
manufacturers.  The  silica  content  of  the  'Tulare'  ore  is  evidently 
largely  secondary.  'Sierra  Standard'  calcined  material  is  obtained 
from  the  ores  of  the  'Standard'  and  'Lindsay'  sections.  A  fifth 
grade,  designated  'Premier'  is  not  put  on  the  market,  but  is  an  inter- 
company grade  utilized  by  the  Kellastone  organization.  It  is  merely 
a  slightly  off-color  'Standard.' 

OAKLAND  MAGNESITE  leasehold.  This  mineral-rights  lease 
covers  a  strip  of  ground  in  Sees.  7  and  8,  T.  21  S.,  R.  28  E.,  between 
the  Harker  mine  and  the  Gill  property  northeast  of  Porterville.  It 
is  in  a  narrow  valley  running  westerly  and  extends  up  the  slope  of 
the  hillsides  both  north  and  south.  In  their  'No.  22  Tunnel'  on 
the  north  side  of  Porterville  Hill  near  the  Harker  ground,  ore  is  being 
taken  out  of  a  winze  where  the  vein  shows  30  inches  wide.  It 
averaged  3'  wide  above  the  tunnel  level,  and  the  ore  is  white  and 
high-grade.  There  is  a  compressor  plant  on  the  Oakland  ground 
which  supplies  air  to  both  these  workings  and  to  those  on  the  Gill 
Lease  over  the  next  hill  to  the  north.  To  the  north  of  the  compressor 
there  is  a  shaft  sunk  on  the  'Rose'  vein  (so  called  because  of  its 
pinkish  color),  but  no  ore  has  been  taken  from  it  recently. 

GILL  RANCH  lease  (see  also  under  Gill  Ranch,  ante).  The  Sierra 
Company  holds  a  lease  covering  all  of  the  magnesite  occurrences  on 
the  Gill  ranch.  The  principal  operations  are  at  present  confined  to 
Sees.  7  and  8,  T.  21  S.,  R.  28  E'.,  north  of  the  Harker  Mine.  When 
visited  by  the  writer  in  November,  1923,  the  work  was  being  done 
l)y  Ed.  Cramer  on  a  tonnage-contract  basis.  Compressed  air  and 
tools  are  furnished  by  the  company.  Cramer  looks  after  the  opera- 
tion of  the  compressor,  and  is  paid  a  stipulated  price  per  ton  for  the 
(Um;  "in  the  bin." 

The  compressor  plant,  located  on  the  'OaklaiKC  ground,  is  an 
Ingersoll-Rand-lmperial,  Tyi)e  10,  ")()  li.  p.  electric  driven.  AVater  is 
hauled  from  Porterville  for  the  cooling  circulation,  and  is  re-used  s(» 
tliat  the  actual  consumption  is  small.  The  two  other  compressors 
at  the  company's  mines  in  the  Success  district  are  of  this  same  type. 
Nearly  a  mile  of  pipe  line  carries  the  air  over  the  hill,  north,  to  the 
lower  tunnel  ("No.  60")  on  which  Cramer  was  working. 

9—39802 


130 


CALIFORNIA    STATE    MINING   BUREAU. 


Tliis  adit  was  then  in  900'  on  a  vein  with  NW.  strike  and  a  width 
averaging'  4'.  It  has  backs  of  165'  to  the  bottom  of  the  old  stopes. 
Preparations  were  being  made  to  raise.  There  are  also  several  veins 
and  prospects  on  the  south  face  of  this  Gill  hill  adjoining  the  'Oak- 
land' ground.  One  adit  ('No.  15')  is  in  500'  and  has  been  stoped  out 
above,  but  there  is  ore  showing  in  the  bottom.  No  work  Avas  being 
done  there  at  that  time. 

CALCINING   PLANT. 

The  calcining  and  grinding  plant  of  the  Sierra  Magnesite  Com- 
pany is  within  the  city  limits  of  Porterville,  directly  on  a  loading 
track  on  the  west  side  of  the  main  line  of  the  Southern  Pacific  rail- 
road. The  plant  was  originally  ])uilt  (1015)  by  the  California  Magne- 
site Company,  being  later  taken  over  l)y  the  American  Magnesite  Com- 
pany, a  subsidiary  of  the  International  Magnesite  Company  which 
operated  the  plant  at  Chula  Vista,  San  Diego  County,  on  ore  from 


Photo  No.  58 — Calcining  plant  of  the  Sierra  Masnesite  Company  at  Porterville, 
Tulare  County.  Cooling-  floor  at  right ;  testing  laboratory  of  the  National 
Kella.<5tone  Company  at  left.      Photo   by   C.  A.   Waring. 

Lower  California,  Mexico.  During  1917-1918,  this  plant  opt'rated 
on  custom  ore  under  management  of  the  American  Refractories 
Company  of  Joliet,  Illinois.  That  company  purchased  crude  ore 
which  met  their  specifications,  at  5i?8.50  per  ton  delivered,  and  supplied 
their  eastern  customers  with  calcined  unground  magnesite  at  a  con- 
tract price  of  $32  per  ton.  City  water  is  furnished  the  plant.  The 
buildings  are  of  substantial  wood-frame  and  corrugated-iron  con- 
struction. 

The  crude  ore  is  received  by  rail  and  auto  truck,  and  dumped  on 
the  ground  near  the  crushers,  which  are  set  below  grade  to  facilitate 
feeding.  The  Ore  is  crushed  in  the  primary  jaw  crusher,  folloAved  by  a 
Telsmith  crusher  in  circuit  Avith  a  trommel,  sampled,  and  carried  by 
chain  bucket  elevators  to  the  storage  bins.  The  furnace  feed  size  is 
^  inch.  From  here  it  passes  through  the  rotary  kilns,  the  discharge 
falling    on    a    mechanical    conveyor   which    dumps    the   hot    calcined 


MAGNESITE   IN    CATJFORXIA. 


131 


I 


132 


CALIFORNIA    STATE    MINING   BUREAU. 


Plate  XI. 


Trucks  or  /?./?.  Qrrs 


N^-4  W/tee//rref  jctyy  Crus/rer 
e/ey^for 


Tromme/,  -?  '  ho/es 


Oversize 


W?  2p  l^^/ree///?cf  jcfyy  cri/sAer 


Urrofers/ze 

r 

f/evctfor 

~T~ 

Sforcrcfe  im 
Aufvmcrf/c  feeoifsr 


ao'x  6' /?ofefry  /0//r.  5//oce/ 
bnck  ///7//7q,  o//  f/ree¥ 


/^serve  K//rr 


Sfee/  eYrera  co/tveyor 
Coo/i/Tcr  f/oor 

I T^ — I 

efctfe         <!ferfe         /yi^/g 


Screw  corveyor 

Se/f  co/tveyor  yv/f/j  AftT<^/Tef/c  pi///ey 

Sfurfsvef/rf  ro/ary  f/re  crus/rer 

^~ 

e/everror 

Z- comp  5/orcrije  6//r,  60 /ors  ostpcrc//y 

Ur/f  of  6-30'  Sfo/re  hurr  /n///s  2^.°  Un/f  6  burr /n)//s 


Screw  corveyor 


e/evefh>r 


Serc/r/zro  bu/?/rer 
/^joer  ///7eaf  burMp  sercAs  /SO/b.  eerc/r 


Flow-sheet  of  magnesite  plant  of  Sierra  Magnesite  Company  at  Porterville. 


A 


MA(iNESITE    IN    CALIFORNIA. 


133 


])rO(ln('t  on  tlio  eooliuii'  platfonii,  to  be  later  sacked  for  sliipmcnt  or 
loaded  ill  Itulk  form  into  railroad  ears. 

There  are  two  rotary  kilns,  one  5'  x  50'.  driven  l)y  a  10-h.  p.  vari- 
able-speed motor  whieh  also  runs  a  small  sample  crusher  and  grinder, 
and  one  6'  x  75'  kiln,  driven  by  a  20-h.  p.  motor  of  the  same  type. 
Only  the  larger  one  was  in  use  in  November.  1923.  The  speed  has 
been  reduced  so  that  the  crude  ore  travels  through  the  kilns  at  the 
rate  of  approximately  1  foot  per  2  minutes,  and  the  capacity  is  65 
tons  of  calcined  niagnesite  in  24  hours  when  both  furnaces  are  oper- 
ated. About  2.2  tons  of  crude  ore  are  required  to  make  one  ton  of 
calcined.  Electric  power  is  furnished  by  the  Mt.  Whitney  Power 
and  Electric  Co.  Crude  oil  is  used  for  fuel  in  the  kilns.  The  oil, 
after  being  raised  to  a  temperature  of  184°  F.,  is  fed  to  the  burners 
under  90  lbs.  pressure,  with  steam  at  100  lbs.  Consumption  of  oil 
amounts  to  1.2  bbl.  per  ton  of  calcined  product.  A  55,000-gallon 
oil-storage  tank  is  provided.  The  kilns  are  lined  with  fire-brick, 
which  must  be  partly  renewed  after  12  to  18  months'  use. 

Twenty-seven  men  are  ordinarily  required  for  operation  of  the 
plant,  nine  being  employed  on  each  of  three  8-hour  shifts.  Other 
help  for  loading,  etc.,  work  in  two  shifts  of  nine  hours  each. 

Fine  grinding  of  the  calcined  material  in  preparation  for  stucco 
and  plaster  mixtures,  is  accomplished  in  12  buhr  mills  in  two  banks, 
so  that  85%  will  pass  200  mesh. 

They  have  adopted  different  burnine-  ranges  for  their  several 
grades,  and  plant  conditions  are  adjusted  to  accommodate  these. 
These  adjustments  make  for  a  uniformity  of  products.  In  calcining 
they  have  found  that  :}-inch  is  the  maximum  feed  size  with  which 
good  results  can  be  obtained  in  the  rotary  kilns,  and  an  average 
of  ^  inch  is  maintained  in  practice.  The  ore  remains  in  the  kiln 
slightly  over  two  hours.  If  the  size  is  doubled.  4  x  the  time  is 
required.  In  the  old  Tulare  upright  kilns,  the  ore  i-emained  5  hours. 
Up  to  7-inch  size  was  fed.  It  was  noted  that  there  were  often 
unburned  cores,  even  with  the  outside  'overdone.'  The  rotary  kiln 
yields  a  more  uniform  product.  The  furnace  man  takes  a  sample  of 
the  burned  material  over  each  24  hours,  and  these  samples  are  put 
through  the  series  of  physical  tests  described  in  preceding  pages 
under  "tests  and  specifications." 

The  NATIONAL  KELLASTONE  CO:\IPANY  of  which  the  Sierra 
IMagnesite  Company  is  an  associate  (being  controlled  by  the  same 
financial  interests),  has  one  of  its  stucco  plants  here,  where  stucco 
mixtures  are  prepared  for  sale  to  contractors  and  material  dealers. 
All  of  the  technical  control  work  of  the  National  Kellastone  Com- 
pany is  carried  on  at  Porterville  in  the  physical-test  and  chemical 
laboratories.  Both  of  these  laboratories  are  especially  and  com- 
pletely equipped  for  such  work.  Because  of  the  high  summer  tem- 
peratures, there  is  a  below-ground  basement  room  under  the  physical- 
testing  building  for  use  in  the  summer  months,  so  that  fairly  uniform 
temperatures  may  be  had  for  testing  throughout  the  year. 

Because  of  their  careful  technical  control  a  uniform  product  of 
guaranteed  behavior  can  be  delivered.  Their  three  commercial 
grades,  with  approximate  chemical  analyses  are  as  follows  (it  being 


134 


CALIFORNIA    STATE    MINING   BUREAU. 


MAGNESITE    IN    CALIFORNIA.  135 

iiiulcrstood  that  the  ji'nai'aiiteod  physical  tests  arc  of  iiu)i-c  \ital 
(M)uccni  tlian  a  specific  chemical  composition)  : 

'Sierra  Standard.'  White  or  li^ht-gray  color  Avhen  «iroun(l;  INIgO 
837f-859i;  ;  C^aO  (under  4%  total;  .1.5%  active);  ALO,  and  Pe.O, 
under  1  %  ;  SiO.  up  to  S'/t .  Ignition  loss  2^/( .  Used  for  finish-coat 
stucco. 

'Tulare  A.'  Cream  color;  :\lgO  85 7c -87 %  ;  Al.,0',  and  Fe.,0,  3%; 
CaO  (37r  total,  1.5%  active)  ;  SiO,  5%-6% .  Ignition  loss  3%.  For 
flooring  finish  coat ;  also  some  for  stucco. 

'Xo.  20'  or  'Base  Coat'  (also  called  'No.  20  B.  C).  Color  varies, 
dark  cream,  light  brown,  etc.  IMgO  80%  ;  CaO  3%c  ;  AlgO,,  and  Fe,0, 
about  4%  ;  Sid,  12%-M%  .  Ignition  loss  4%  .  For  base  coats,  l)oth  in 
stucco  and  tloors. 

In  November,  1923,  there  were  75  men  employed  in  the  mine,  and 
a  total  of  49  in  the  plant,  laboratories,  and  office,  including  9  in  the 
National  Kellastone  unit.  A  larger  number  of  men  are  employed  in 
the  several  mines  of  the  company  during  the  summer  months. 

The  otificers  of  the  Sierra  Magnesite  Company  are:  S.  H.  Barrows, 
l)resident.  Chicago,  111.;  J.  A.  Bernhard,  Balfour  Bldg.,  San  Franci.sco; 
and  at  Portrrville  the  following — 

Arthur  Deleray,  manager;  Max  Y.  Seaton,  technical  director;  J.  B. 
I'erry,  mine  superintendent;  L.  A.  Laidlaw,  plant  superintendent; 
C.  R.  Olsen,  chemist. 

Bibliofjrapln/:  Cal.  State  Min.  Bur..  Reports  XV,  pp.  919-922, 
928-931,  936-940:  XVII,  p.  259;  XVIII,  pp.  531-535;  XX,  pp. 
30-31;  Bull.  38.  ])]).  333-334.  V.  S.  Geol.  Surv.,  Bull.  355,  pp. 
46-48:  Bull.  540,  pp.  509-511. 

Simmons  Ranch  Deposit  (Bartlett  Lease).  There  are  a  num- 
ber of  coiiipai-ativciy  thin  xciiis  of  magiiesite,  on  or  near  the  top 
of  a  .serpentine  hill  about  a  mile  south  of  the  schoolhouse  at  the 
Simmons  Ranch,  8  miles  southeast  of  Porterville.  The  hill  is 
a  portion  of  the  outside  range  of  foothills  of  serpentinized  rock. 
The  country  rock  is  a  dull,  brown  serpentinized  peridotite  similar 
to  that  near  Porterville.  Some,  but  not  many,  of  the  nuignesite 
veins  reach  2  feet  in  thickness  for  short  distances,  (generally  they 
ai-e  discontinuous  and  irregular.  A  small  amount  of  magnesite  of 
excellent  quality  has  been  mined  on  the  west  side  of  the  hill  from 
a  nearly  vei'tical  vein  running  parallel  to  the  course  of  the  hill  and 
i-anging  from  10"  to  18"  in  thickness.  On  the  east  side,  near  the 
top  of  the  hill,  arc  other  veins.  Development  has  been  by  shallow 
open  cuts  and  short  adits.  It  was  operated  under  lease  by  W.  P. 
Bartlett.  superinteiulent  of  the  Tulare  Mininu'  Company.  C.  W. 
Simmons,  Deer  Creek,  owner. 

Bibliograplnj :  Report  XV.  p.  923. 

The  Tulare  Mining  Company  owns  the  E.-J  of  the  NE.j  of  Sec. 
28,  T.  22  S..  R.  28  K..  M.  D.  M.,  in  the  Deer  Creek  ^Mining  Dis- 
trict. This  territory  is  southeast  of  Porterville  and  southwest  of  the 
calcining  plant  and  mine  at  IMagnesite,  these  three  points  forming 
a  triangle  whose  sides  are  about  eight  miles  in  length.  There  is  no 
limber  on   the  I'ounded   hills  which  ToiMii   the  siifface.  but    water  can 


136 


CALIFORNIA    STATE    MINING   BUREAU. 


MAGNESITE    IN    CALIFORNIA.  137 

l)e  ol)taiiied  from  Deer  C'reek.  This  property  was  not  taken  over 
l>y  the  Sierra  Magnesite  Company  with  the  other  holdings  of  the 
Tulare  Company. 

The  magnesite  occurs  as  veins  in  serpentinized  peridotite,  which 
so  far  as  developed  in  1917,  appeared  to  be  narrow  and  not  numerous 
enough  to  be  worked  with  much  profit  by  the  methods  used.  Four 
men  were  hand  mining  in  open  cuts  and  sorting  old  dump,  getting 
out  from  6  to  7  tons  per  dav.  The  crude  ore  was  hauled  to  Porter- 
ville. 

Wood  Ma^esite  Mine.  Small  magnesite  veins  from  3"  to  12" 
wide  are  found  on  the  southeast  slope  of  Badger  Hill  in  See.  6,  T. 
19  S.,  R.  27  E.,  M.  D.  M.  The  only  work  done  has  been  by  open  cuts 
and  these  are  shallow  and  cover  but  a  small  area.  The  property  is 
situated  3  miles  east  of  Exeter,  the  nearest  town,  and  is  owned  by 
J.  J.  Hamilton,  Yokohl  Valley.  It  was  leased  to  F.  G.  Hude  and  L.  L. 
Wood  of  Lindsay,  California.     Idle. 

Bibliography :  Cal.  State  :\Iin.  Bur..  Report  XV,  p.  940. 


];is 


CALIFORNIA    STATE    MINING    BUREAU. 


TUOLUMNE  COUNTY. 

Althoutih  gold  furnishes  the  major  value  in  the  mineral  output  of 
this  'Mother  Lode'  county,  its  structural  and  industrial  mineral 
deposits  are  not  to  be  considered  unworthy  of  exploitation. 

Tuolumne  ranks  first  among  the  counties  of  the  state  in  the  pro- 
duction of  marble ;  and  limestone,  dolomite  and  other  non-metallics 
add  to  its  mineral  wealth.  ]\Iagnesite  has  only  recently  been  pro- 
duced in  commercial  quantities  though  there  are  a  number  of  deposits 
in  the  prospective  stage. 

Gray  Eagle  Magnesite  Claim.  Five  mining  claims  have  been  located 
in  the  Chinese  Camp  IMining  District,  in  iiec.  16,  T.  1  8.,  R.  14  E., 
M.  D.  M.,  of  which  four  are  for  copper,  and  one,  known  as  the  Grey 
Eagle  claim,  is  for  magnesite. 


I 


Photo  No.  62 — Vail  and  MaxweU  calcining  plant  at  Chinese  Camp,  Tuolumne  County; 
for  handling  magnesite  from  the  Gray  Eagle  mine. 

The  Grey  Eagle  is  situated  two  miles  from  Chinese  Camp  at  an 
elevation  of  1250' ;  and  is  owned  by  D.  E.  Stratton,  Chinese  Camp. 
The  surface  is  wooded  with  digger  pine,  and  a  creek  crosses  the  claim 
within  100  yards  of  the  deposit.  It  was  operated  in  1922,  by  Cum- 
niings  &  Regan,  lessees,  who  shipped  several  hundred  tons  of  crude 
ore  to  Oakland  for  plastic  purposes. 

It  was  taken  over  in  1923  under  lease  by  H.  R.  Vail  and  John  P. 
Maxwell,  820  Syndicate  Bldg.,  Oakland,  and  Avhen  visited  in  Novem- 
ber, they  were  building  a  calcining  plant  (see  photo)  on  the  Sierra 
Railway  at  Chinese  Camp.  The  kiln  is  of  15  tons  calcined  product 
daily.  The  ore  is  hauled  from  the  mine,  a  distance  of  two  miles, 
by  motor  trucks. 

The  magnesite  occurs  as  a  lens  along  a  contact  of  serpentine  and 
schist,  with  strike  N.  65°  E.  and  dip  45°  NW.    It  is  developed  through 


MAGNESITE    IN    CALIFORNIA.  139 

an  adit  which  crosscuts  it  at  310'  in,  thence  a  drift  has  t)eeji  run  50'. 
This  level  is  at  a  depth  of  98'  below  the  outcrop,  and  84'  ])el()W  the 
upper  drift,  which  Avas  driven  from  the  bottom  of  the  shaft.  In  the 
stope  the  vein  shows  8'  to  10'  in  width.  The  shaft  has  a  depth  of  64' 
with  a  drift  80'  east.  Mining  of  the  ore  was  being  done  by  contract. 
Analyses  of  five  or  six  samples  taken  along  the  outcrop,  made  by 
Curtis  and  Tompkins,  show  the  following  averages: 

Per  cent 

SiOa    0.60 

A1.0:,    0.22 

Fe..Oi   1.08 

CaO    1.56 

MgO     .. 45.40 

Ignition   loss   51.01 

99  S7 
Purity   as   MgCOj 94.94% 

Bibliography:  Cal.  State  .Min.  Bur.,  Heport  XX,  pp.  22-23.     U. 
S.  Geol.  Surv..  Bull.  355,  pp.  51-52. 

Monarch  Mine  Company.  ^I.  Pavolich  of  Stent,  reports  (^larch, 
1925)  uncovering  a  l)()dy  of  mairnesite  5  feet  wide  on  this  property. 
1|  miles  from  Chinese  Camp. 

Peter  Maki  Claims.  Three  magnesite  claims,  the  Sunshine,  Snow- 
drift and  one  other,  are  located  in  Sec.  6,  T.  1  S.,  R.  14  E.,  M.  D.  M. 
about  one  mile  southwest  of  Chinese  Camp.  One  claim  comes  up  to 
the  railroad  near  the  railroad  Avater-tank  south  of  Chinese.  The 
property  is  unecjuipped  and  no  ore  has  been  shipped.  The  owner 
stated  he  had  50  tons  in  a  pile,  luit  specimens  which  he  showed  a.s 
an  average  of  the  pile  carry  considerable  chalcedon\'  and  wouhl  not 
be  marketable.  A  little  prospecting  deveh)pment  was  being  done 
in  November,  1923.     I'eter  j\Iaki,  owner. 

White  Rock  Magnesite  Mine.  This  property  is  also  in  the  Chinese 
Camp  district,  in  the  southwest  corner  of  See.  6,  T.  1  S.,  R.  14  E., 
M.  D.  ]\I.  It  lies  on  a  pine-covered  rounded  hill.  \Vat«'r  lias  to  be 
hauled  from  Chinese  Camp. 

The  deposit  looks  like  a  vein-filling  along  a  brecciated  zone,  the 
mineral  perhaps,  being  carried  down  from  the  surface  and  recrys- 
tallized  in  veins.  The  magnesite  vein  strikes  N^.  85°  E.  and  dips  80° 
S.  varying  in  Avidth  from  1'  to  2'.  A  60'  incline  shaft  having  one 
compartment  and  mauAvay  has  been  sunk  on  the  vein,  and  it  has 
also  been  open-cut  along  the  surface  from  3'  to  6'  for  over  1000'. 
The  vein  is  only  a])out  1'  Avitle  in  the  bottom  of  the  shaft  and  did  not 
justify  the  expenditure  upon  it. 

The  magnesite  is  of  good  (piality  but  it  has  been  poorly  mined, 
leaving  a  great  deal  of  serpentine  Avith  it.  xVbout  one-half  a  car-load 
might  be  sorted  from  a  pile  laid  out  at  the  mine  for  shipment. 

There  had  been  a  30'  headframe.  1000-gallon  Avater-tank,  800-gallon 
wooden  tank,  60-h.  p.  steam  boiler,  hoist,  and  compressor  on  the 
property,  but  ruined  by  a  fire. 

Three  cars  of  ore  are  said  to  have  been  shi])ped  from  the  mine  to 
the  Sedan  Calcined  Magnesite  Company,  Emeryville,  California,  in 
1917.    The  property  Avas  leased  to  E.  E.  Schmitz  and  Frank  Nyland 


140  CALIFORNIA    STATE    MINING    BUREAU. 

but  the  lease  expired.  It  was  later  leased  by  Harry  Van  Zanter 
and  Mr.  Prentice  who  were  to  continue  sinking  the  shaft  on  shares 
with  Henry  Sims,  the  owner.  The  deposit  will  not  pay  to  work  with 
the  equipment  on  the  ground  and  present  facilities.  No  further 
commercial  production  has  been  made  to  the  end  of  1924.  Henry 
Sims,  owner,  Chinese  Camp. 


INDEX. 

Page 

'Active'  oxide 24 

Adeline  mine -- 106 

Afton  deposit 72-75 

map  of -- 72 

outcrops  of 73 

Aggregates,    addition    of 23-25,  30 

Alameda  County 36,   37,  40-43 

mines   in 40-43 

production  in _- 36,  37 

Albertz   ranch   deposits 89 

Alloys  of  magnesium -- 20 

American  Magnesite  Company 81,  103,  106,  124,  130 

Magnesium  Corporation 21 

Refractories  Company 106,  123,  130 

Analyses  of  magnesite 15,  49,  56,  62,  68.  74,  95,  99,  102,  113,  126,  139 

Anderson   property -- 44 

Arnstein  lease , 79 

Avery   lease    -- 124 

Bachler  mine 44 

Bald  Eagle  claim 98 

Bartlett  lease 135 

Battenburg  Refractory  Magnesite  mine 89-91 

Bay  Cities  Water  Company -- 79 

Bedell  property 53 

Berry   strain   gauge 33,  34 

Berthenia  mine   53 

Bibliography   (general)    39 

(see  also  under  individual  mines) 

Bissell  mine 47-50 

analysis  of  magnesite  from 49 

section   of   -_ 48 

Black  Bird  Valley  mine 79 

Blake,  W.  T.,  cited -- 110 

Blanco  mine 16,  53,   54,  55 

Blanket  veins  in  Marker  mine 110,  112,  114 

Blue   Crystal   group 106 

Boggs  property 107 

Boiler-scale,  prevention  of 19 

Bonanza   mine 66 

Booth,  Garrett  and  Blair,  cited 95 

Borchsenius  claims 98 

Bradford  ranch  deposit 16,  78 

Bradley,  W.  W.,  cited 44,  51,  95 

Buckling  of  cement 26 

Buhr  mills,   fine  grinding  in 133,  136 

Burgans  ranch   deposit 91 

Burnett  ranch  deposit 78 

Burning,  effect  of,   on  magnesite 15 

furnaces  used  in 22 

methods  of   22 

Burr  Bros,  lease 107 

Butcher  mine 16 

Calcining,  effect  of.  on  magnesite 15 

furnaces_-_22.   42,   45,   51.   54.   58.    68,    69.    70,    84,    85,   88.   90,    96.    116,   121.    131 

methods  of 22 

time    of    133 

Calcite.  chemical  rebition  of,  to  magnesite 11 

California  (Jraphite  Company 52 

Magnesia  Company 37,  107,  m 

Magnesite  Company _ 98.  106,  107.  109 

total  production  of  magnesite  in 37-38 

Carbon  dioxide  in  magnesite 12.  15 

Carbonic  acid  gas,  utilization  of 19 

Carroll    ranch    deposit [ I07 

Causes  of  unsatisfactory  installations Ig 

Caustic   magnesite    18 


142  INDEX. 

Page 

Cedar  Mountain  district,  early  production  from 37 

mine 16,   40-41,  42 

Cement   (see  also  'oxychloride') 17—18 

Chamberlain  ranch  deposits -- 107 

Characteristics  of  magnesite 11—13 

Chart  of  magnesite  production  in  California 36 

Chemical  and  physical  tests  for  magnesium  oxychloride 21—27,  28 

Chiles  Vallev  mines 53 

Clarke,   R.   H -- 82,    84,  85 

Cleveland   mine 53 

Cliffside  Magnesite  Company 72 

Cochrane    ranch    deposit 16,  79 

Coghlan   property 118 

Color   of  cement . -- 30 

Conchoidal   fracture 10,  12 

Concrete  design  on  different  princinle  from  oxychloride  cements 25 

Cone    lease    -- SO 

Consistency  of  cement i 30 

Consumption  of  magnesite  by  copiier  converters 39 

for    plastic    iiurjioses 39 

in   open-hearth   practice , 16 

of  oil  for  fuel 51,   68,   113,133 

Contracting  of  cement 26 

Costs   of  magnesite   production -- 39 

freight   113,   125 

fuel    ■_ ■  51 

hauling 51,  55,  56,  58,  70,  S9,  125 

labor 111,  124 

Cramer  contract 129 

Creon  deposit 89 

Crocker  property — 41 

Cross-bending   tests    31—32 

Cross  ranch  deposit : 107 

Curtis  and  Tompkins,  cited 139 

Dead-burned    magnesite 18 

in   California 54,   69,    70.  90 

Deer  Creek  mine 107,123 

De   Moulin   mine 107-108 

Detert   and    Elder 16 

Detert   mine   53 

Dinuba    Magnesite    Company 108 

Dolomite,  chemical  relation  of.   to  magnesite 12 

Doyle    lease 109 

Dumont    property    108 

Duncan  mine 108-109,  117 

Duralite   Company 76 

Eakle,   A.   S.,  cited 58.  59 

Eckel.   E.   C.   cited 12.  39 

Eckert  ranch  deposit 92 

Elder,    Geo.    W 74 

Elder  mine 53 

El    Mirador   Magnesite    Company 106 

Eng.  Soc.  Western  Pennsylvania,  cited 18,   39 

Epsom  salts 20 

Expanding  of  cements — 26 

Fairview  mines 109 

Fenster  deposit — 99 

Ferguson  mine 44,  45 

Fillers  used 17,  23,  25 

Fine    grinding 23,   30,    133,    136 

Fire  brick 13 

Fischl  property 71 

Plat-hearth    calcining    furnace 42 

Flooring     18 

Flow-sheet  of  Sierra  Magnesite  Company  plant 132 

Fresno  County 36,   37,  44-46 

mines    in 44-46 

production    in 36,   37,   44 

Fresno    Magnesite    Company 44 

Furnaces 42,  45,  51,  54,  58,  68,  69,  70,  84,  85,  88,  90,  96,  116,  121,  ^ll 


I 


INDEX.  143 

Page 

Gale,  H.   S.,  cited 9,  13,  1(5.  47.  tJl,  fi2,  66,  83.  93,105 

Ga.sh  veins  in  Marker  mine 112,  115,  117 

General  Electric  Company,  special  uses  of  magnesite  by 99,  101 

Geology  of  magnesite   deposits 

47,  56-57,  61-62,  73-74.   82-83,  89,  93,  98.  105,  113-116,   126-129 

Germany   importations   from -- 20,  23 

Gilliam    Creek    properties 91,  96 

Gill    ranch    deposits 109-110.  129 

leases 123,   129-130 

Gilmore  needle  for  setting  time  tests 24,  31 

Glue-joint    principle 23 

Grades  of  ore  mined  by  Sierra  Magnesite  Company 129 

of  product   marketed 135 

Gray  Eagle  claim 138 

Grinding,  fine 23,  30 

Guerneville    Farms    Company 92 

Gustine  Magnesite  Company 98,  99-101 

special,   high-grade   ore    from 99 

Hamilton   property -_ 137 

ranch   deposit    , 110 

Hanks,   H.   G.,  cited . 9 

Hajipy  Canon  magnesia  claims 77 

Marker  Estate  jirop'erties 89,  9(1-97.  Ill 

mine 37,   110-117.  12:; 

blanket  veins  in 110.    Wl.  Ill 

gash  veins  in 112.   11".,  117 

geology  of -- 113-1  Id 

wages   paid   at 1  1  I 

quarry     1(1 

Hawley  I'ulp  and  Paper  Company 108.  117-118 

Hayden  mine ' 118 

Mayes   ranch   deposit 42 

Meadberg  property -_ 118 

Mealdsburg   Marble  Company 91 

Memet  mine 61-64 

ore   sorting   at 62 

Mess.  P.  L.,  cited 20,  21,  52,  56.  61,  83,  90.  105.  110.  113 

Mixon    ranch    deposit 52 

Hoff  and   Marker  lease 111 

Hoff  Asbestos   Company 41 

Magnesite  Companv,   Inc 79 

Hoff.  .John  D r,5 

Hoff-I'rice  Company IG,   69,  SI 

Howard   Cattle   Comjiany 100,  101 

Huguenin.  Emile 8 

Humidity,    effect    of 25 

Hydro-magnesite _- 43,    71,  125 

Imports   of  magnesite 38-39 

Industrial    uses    . 13—21 

Innes-Speiden  and  Company,   Inc 65 

International  Magnesite  Company 49,   76,   124,  130 

Iron,    in  magnesite 15,  jg 

.lackson   mine 10,  7<( 

.Icrome  group : CG,  7] 

Jour.   Amer.    Ceramic   Society,    cited ;^9 

Joyner   Bros,   mine 118 

Kern   County 36,   37,   47-50 

mines  in 47-50 

production    in    36,  37 

Kings  County,  mines  in 51 

Magnesite  Company ' 51,  53 

<iuicksilver  mine   51 

KuUing  deposit 12,   14,89 

Laizure,    Clyde    Mck ^ 

cited   9g 

Langley-Cook   lease   107,  123 

lA^ster  projierty 121 

Ijherzolite,  serpentinized 56,  83 


144  INDEX. 

Page 

Lindsay  Mining  Company 103,  105,  118,  123 

mine — 124-125,  127 

production  of 125 

Linear  change  in  cements 34 

Lime,  in  magnesite 15,   16,  27 

'active'   and   'inert' 27—28 

Little  Bear  mine 59 

Logan,    C.    A 8 

Los  Angeles  County,  magnesite  in 52 

Madeira   deposit    — 91 

Magnesco   Refractory   Company 65 

Magnesia  alba 20,  97 

Magnesite,  analyses  of 15,  49,  56,   62,  68,   74,  95,  99,  102,   113,  126,   139 

chart  showing  production  and  value  of 36 

consumption  of,  in  open-hearth  practice 16 

geology  of  deposits  of 

47,  56-57,  61-62,  73-74,   82-83,   89,  93,  98,  105,  113-116,  126-129 

history  of,   in   California 9,  37 

imports  of   _- 38-39 

map  showing  locations  of  deposits 10 

oxychloride  cement  from 21—34 

production    of    . 34-38 

properties  and  origin  of 11—13 

Refractories    Company ; 107 

tariff  on   38-39 

uses   of 13-21 

value  of   35-38 

war-time  activity  in 11,  35-37 

Washington  deposits  of 9 

Magnesium  chloride 17,  19,  23,   30 

preparation  of,  from  salt-works  bitterns 19 

metallic 20-21 

Maki  claims 139 

Maltby,  C.  S 37,  54,  58,  70,  82,  84,   85,  88 

Maltby  No.  1  mine 37,  79,   81-87 

maps   of 82,  84 

No.  2  mine 1 37,  54-55 

dead-burned  magnesite   from 54 

No.   3  mine — 37,   66-71 

dead-burned  magnesite   from 69,  70 

Map  of  Afton  group 72 

California  showing  locations  of  magnesite  deposits 10 

Maltby  No.   1   mine  workings 82,  84 

Tulare  County  magnesite  deposits 104 

Western  Magnesite  Development  Company  properties 82 

Matthai  mine 53 

McKiernan  mine 119 

McLaughlin  mine   — 16 

Medicinal  uses 20 

Meeker   ranch   deposit 91-92 

Meerschaum    : 12 

Melville  ranch  deposit 92 

Mendocino  County 36,   37,  52 

mines   in 52 

production  in 36,  37 

Mentz  property   __ 119 

Merced  County,  production  reported  in 36,  52 

Merryman  Fruit  and  Land  Company 119 

mine    119 

Metallic  magnesium 20-21,  80 

alloys  of 20 

Mineral  Products  Company 99 

Mitchell  mine 121 

Mixtures  for  cement 23-25,  30 

Monarch  mine 139 

Monterey  County,   magnesite   in 53 

Montgomery  property    121 

Napa  County 36,   37,   53-58 

early  operations  in 53 

mines   in   53-58 

production  io 36,  37 


INDEX.  145 

Page 

National  Association  of  Oxychloride  Manufacturers 28 

Kellastone   Company 130,   133-135 

grades  of  products  made  by 135 

technical  control  of  products  by 133 

Nevada  County,  magnesite  in ^ 58 

Niagara  Falls,  manufacture  of  metallic  magnesium  at 21 

Oakland    Magnesite   Company 123 

mine 114,  123,   128,   129 

O'Connell  Bros,  ranch  deposits 79-80 

Ostrander  property 119 

Oxychloride  cements 17-19,  21-34 

applications  of 17-18 

not  hydraulic 25 

specifications  for 28—34 

testing  of    21-34 

Pacific  mine !(;_  80—81 

Packages 29 

Paint,  use  as 19 

Palmer,   Chase,  cited 15 

Panama  Canal,  shipments  of  magnesite  via 11,  89,  92 

Paper  manufacture ! ^ 19 

Patterson  &  Western  railroad 81,  99 

Peters,  A.  J.,  cited 95 

Physical  and  chemical  tests  for  magnesium  oxychloride 21-27,  28 

Piedra  Magnesite  Company 44 

mine 44-45 

Placer  County 36,   37,   59-60 

mines  in 59-60 

production    in    36,  37 

Properties  Company 59 

Plastic  Magnesite  Company -- 101 

Plastic  uses 17-19,  21-34 

fillers  in 17,   23,  25 

mixtures    for 17,  25 

Pope  Valley,  deposits  in 53 

mine    56 

Portervllle  district 103-106 

Magnesite  Company 103,  110,  116,  123 

Powers  lease   45 

Prices  of  magnesite 35 

Priest  mine 55 

Production  and  prices  of  magnesite 34-38 

Properties  of  magnesite 11-13 

Pure  Carbonic  Company 117 

Quaker   group    74,  75 

Quicksilver,  furnace  used  in  calcining  magnesite 51,  55,  85,  88 

Quinto   claim    102 

Creek  deposits 52,  98,  99,  101 

Ravalli   lease   119 

Red  Mountain  deposits 78,  98 

Magnesite  Company 16,  98 

Refractory  Magnesite  Company 89-91 

uses    13,    15-16 

Rex  Plaster  Company 49,  123 

mine 124 

Righctti    ranch    deposit 78 

Riverside   County 36,    37,    61-65 

mines   in    61-65 

production   in 36,  37 

Rotary  kilns 54,  69,  70,  85.  116,  131 

Sample    mine    45 

Sampling 27,  29 

Sampson  Peak  mine 37,  64,  66-71 

furnaces  at 68,   69,  70 

outcrop  of 64 

San  Benito  County 37,  65,  66-71 

mines   in    66-71 

production  In 37 

10—39802 


146  INDEX. 

^  Page 

San   Diego   County yg 

Sanitary    installations   : . ~        jg 

Sart  Luis  Obispo  County,  magnesite  in I Z__Z        76 

Santa  Barbara  County,  magnesite  in 77 

Santa  Clara  County ___!_ 36    37    7g_8g 

mines   in    .'_78— 88 

production  in   ; 3g   37 

Santa  Margarita  Island  magnesite,  calcined  at  Chula  Vista,  California '  76 

Scherer,   Robert,  cited 17 

Schindler  group __        102 

Schmitz-Nyland   lease ]__Z ^IIIIIII   .  140 

Schrei  property II_I 106 

Scott,  fire-ore,  quicksilver  furnace,  used  in  calcining  magnesite 51,  85,  88 

Seaton,  Hill  and  Stewart,  cited 21,  22,  28 

Seaton.  M.  T.,  cited 2I,  24,' 28,' 39 

Sedan  Calcined  Magnesite  Company 102,  139 

Selby  Smelting  and  Lead  Company,  cited 95 

Senate  Finance  Committee  hearing  on  magnesite,  cited 39 

Sepiolite 12 

Set,   time   of 24    31 

Sherlock  lease '  gQ 

Siebert   property    , ^_. 4g 

Sierra  Magnesite  Company .-^ 10,   24,   28, 

37,  106,  109,  110,  111,  117,  118,  120,  121,  122,'  123-13*5,  136 

calcining  plant  of 130,  131 

classification  of  ore  .by__ , 129 

flow-sheet    of ^ ^ 132 

grades  of  ore  mined ._^ 129 

Silica    in    magnesite _15,  is 

Sill  and  Sill,  cited . I_     '74 

Simmons  ranch  deposit 135 

Sims   property ^ 140 

Sinclair  Bros,   plant 45,  46 

Snowflake  mine 37,   54,   55-56 

Snyder   property 45^  46 

ranch   deposit   -_ __. 92 

Soda  Creek  mine 16,   53-54 

Sonoma  County 36,   37,   89-97 

mines   in ' . 89-97 

production  in , 36,  37 

Magnesite  Company 14,  16,  89,  92-96 

analyses  of  magnesite  from 95 

geology  of  deposits  of — 93—94 

rotary  kiln  of 95 

Sorel    cements    i 17 

Sorting  magnesite  ore 55,  62,  64,  85,  116,  127 

Southard  ranch  deposit — 52 

Southern  Pacific  Company 49 

Specifications  for  magnesium  oxychloride  cements 21,   22,  28—34 

Sprague-Keasby  Asbestos  and  Magnesia  Company 59 

Spreckels  Bros.   96 

Standard  group  71 

Magnesite  Company 79,  81- 

specifications  and  tests 28-34 

Stanislaus  County ^ 37,   98-102 

mines   in    ^ 98-102 

production  in — 37 

State  Mining  Bureau  reports,  cited 9,  18,  39,  52,  103,  123 

Stauffer  Chemical  Company,  cited 95 

Steam-pipe  covering : 19- 

Stewart  mine 107 

Stock   properties    79,  81 

Stockwork  veins — ---' 61,   126,    127 

Stone,  Ralph  W.,  cited 52 

Storage    29,  31 

Stratton  property 138. 

Strength  tests 27,  31-34- 

Sullivan   property 59 

Sulphite  process  of  paper  manufacture,  use  of  magnesite  in 11,  19 

Superior  Magnesite  Company 71 

Sweasey,   F.   R 57,  58 

Swindell  furnace 41,  42 


INDEX.  147 

Page 

Tariff  on  magnesite 38—39 

Tarpey  property 44 

Temperature,  effect  of 25 

Tensile  strength  of  cements 34 

Testing  magnesium  oxychloride  cements 21—34 

Terrill  lease 46 

'Thin  glue  joint'  principle 23 

Thorpe,  T.  E.,  cited 39 

Time    of  set 24,  31 

Towle,   deposits  near 60 

Tucker,   W.  Burling 8 

cited 105,  113 

Tulare   County 36.   37,  103-137 

map  showing  deposits  in 104 

mines   in    103—137 

production  in 36,  37 

Mining  Company 16,  54,  55-56,  103,  109,  121,  123,  135.  137 

mine   125-129 

geology  of 126-129 

Tuolumne  County 36,   37,  138-140 

mines    in    - 138-140 

production  in — 36,  37 

Uses  of  magnesite 13-21 

U.  S.  Geological  Survey,  cited 9,  11,  15,  18.  20,  37,  39,  56,  82.  95 

Vail  and  Maxwell  plant 138 

Vance  property 46 

Vassar    ranch    deposit — 52 

Vertical  or  stack  kilns 45,  58,  68,  69.  85,  88,  90,  96,  121 

construction  of,  at  Sampson  mine 68.  69 

Vicat  needle,  not  applicable 24 

Walker's  Pass  deposit — 50 

Walters  mine 56 

Ward  mine : 44-45 

Waring,  Clarence  A 8,  48.  61.  63.  72,  73.  110.  120 

cited 59,  125.  126 

Warping  of   cements 26 

War-time  activity  in  magnesite 11,  35—37 

Warwick  mine '- — 16,  80 

Washington,  magnesite  in — 9,   12,  16 

Water   resistance    tests 26 

Weber  ranch  deposits -- 79 

Weissman  lease 108 

Wellman-Lewis  Company -- 65 

Western  Carbonic  Acid  Gas  Company 89,  96 

Magnesite  Development  Company 16,  37,  51,  79,  80.  81-88 

outcrop  of   83 

W^heeler.  W.   C,  cited 95 

White  Diamond  workings,  map  of 84 

Queen  mine — 16.  82,  86 

Rock  mine    (Napa  County) 16,   56-58 

Rock  mine  (Tuolumne  County) 139-140 

Winchester  deposit 61 

Winship  properties 42-43,    79,  87 

W-K  Company   98 

Wood-pulp  paper  manufacture 19 

Woods  mine 137 

Yale,  Chas.  G.,  cited 11 

Yordi  ranch  deposit 92 


39802     9-25     1500 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.00  ON  THE  SEVENTH  DAY 
OVERDUE. 


8  7  JAN  '60  LU 

OCT  1 6  ^^ 
RECEIVED 

OCT  2  6  iba^ 


JUM301995 

JUL  2  a  1994  «tC 

RECEIVED 
M  2  5  ,93^ 

PHVSIMLSCS.LiSfiARi' 
JUN  5  0  2002 


JUti  2  e  2002 
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Book  Slip-15m-8,'52(A257384)458 


PHYSICAL 
SCIENCES 
LIBRARY 


CIBRART 

BXXVERSITY  OF  CALIFQKN1K 

DAVIS 


9<1580 


m 
i 


UNIVERSITY  OF  CALIFORNIA,  DAVIS 

nil  mill  II  nil  iiiiii  ii  iiii  fiiiij 


3  1 


75  01696  1677 


